DP or exhaust?

cn555ic · 01-26-2008, 10:59 PM

I was wondering if you get DP with stock exhaust, would it be the same as getting a catback exhaust system and no DPs as far as HP is concerned??
Obviously getting both would be the most HP gained, but my question is, if either option used, which one would gain more HP. If you get DP the stock exhaust would restrict the flow at the end, but if you get exhaust with the stock DP's, I think it would produce less restriction towards the end!!! I would like to know what you guys think..

oct1285 · 01-26-2008, 11:10 PM

well if you just installed dp's and no exhaust then I can't forsee any real hp gain but your turbos might spool up faster...maybe. And your throttle response might change too. Iono I'm basing this off of my past experience with a WRX

NPDAN · 01-26-2008, 11:22 PM

how much different are after market downpipes than stock?

RetroGamerJP · 01-26-2008, 11:23 PM

I actually lost about 8 HP... with exhaust only... gained about the same in TQ though...

stillclaimndp · 01-27-2008, 12:02 AM

terry got A LOT of power with catless downpipes and stock exhaust... way more than he got out of just cat back...

RMRC · 01-27-2008, 12:04 AM

Good question. For emissions purposes I want UR catted DPs with stock exhaust but I'm not sure there will be any gains. Looking forward to the responses.

E90ice · 01-27-2008, 12:07 AM

Quote:

Originally Posted by cn555ic

I was wondering if you get DP with stock exhaust, would it be the same as getting a catback exhaust system and no DPs as far as HP is concerned??
Obviously getting both would be the most HP gained, but my question is, if either option used, which one would gain more HP. If you get DP the stock exhaust would restrict the flow at the end, but if you get exhaust with the stock DP's, I think it would produce less restriction towards the end!!! I would like to know what you guys think..

I'm not sure if the stock cat-back would restrict much. I don't think we have really much evidence to support the fact that stock cat-back is restrictive.

I would get the DP's. Definately worth it. Especially if you are runing PROcede and Shiv is coming out with a custom map.

Supramano · 01-27-2008, 12:09 AM

ive heard there are more gains to be had when putting dps before exhaust. Something to do with opening the restriction earlier is better than later. catless dps with stock exhaust will produce better gains than an aftermarket catbck exhuast(not just section 3 mufflers). I think the dps which are the primary cats cause the most restriction in the exhaust system.

bullmrkt · 01-27-2008, 12:13 AM

DP's first.

rideelement247 · 01-27-2008, 12:17 AM

Quote:

Originally Posted by Supramano

ive heard there are more gains to be had when putting dps before exhaust. Something to do with opening the restriction earlier is better than later. catless dps with stock exhaust will produce better gains than an aftermarket catbck exhuast(not just section 3 mufflers). I think the dps which are the primary cats cause the most restriction in the exhaust system.

+1

Spot on

.

Of course, adding a simple catback adds in a little more whp. No need for HUGE piping though.

Supramano · 01-27-2008, 12:38 AM

Quote:

Originally Posted by rideelement247

+1

Spot on

.

Of course, adding a simple catback adds in a little more whp. No need for HUGE piping though.

Yeah i did catted dps and exhaust...main reason for exhaust ws for sound and weight...not so much hp...you do save like 30lbs or more with aftermarket...every little bit helps imo.

Gen_E92 · 01-27-2008, 01:44 AM

I would go with DP if I have a E93, makes more power than a cat-back and not much louder than stock. Just not a fan of loud verts unless it's exotic like Ferrari/Lambo etc.

Sniz · 01-27-2008, 02:22 PM

cn...i'm in the same situation. I'm thinking of running catless downpipes and the stock exhaust for awhile. If I do that, I'll eventually go with a custom exhaust w/ a high flow cat at the front. I dont want to be completely catless.

boosted305 · 01-27-2008, 09:59 PM

interesting.....

just curious...

how does it sound with catless DP's and the stock exhaust?

rideelement247 · 01-28-2008, 09:07 AM

Quote:

Originally Posted by boosted305

interesting.....

just curious...

how does it sound with catless DP's and the stock exhaust?

I haven't done it personally, but I hear that it is just a little bit louder and deeper than stock. Your stock exhaust has an X pipe, cats, and mufflers which help kill the rasp from the downpipes. I do not think it would be a problem going catless DP and stock exhaust.

Ultimate Racing · 01-28-2008, 11:06 AM

Everyone always seem to forget that our downpipe (catless and catted) dyno results are with stock catback!

Darryl
www.ultimate-racing.com

Sniz · 01-28-2008, 11:16 AM

Quote:

Originally Posted by Ultimate Racing

Everyone always seem to forget that our downpipe (catless and catted) dyno results are with stock catback!

Darryl
www.ultimate-racing.com

Darryl,
What are we looking at here? is that stock, catted, catless? Also why are the boost level different on all 3? Do the new downpipes allow for more boost on the same ECU settings?

judec · 01-28-2008, 11:19 AM

nope, we dont, at least me not. No question DPs are beneficial. The question is how much are they restricted by stock catbacks under stock boost and how much when running tunes. Gonna ask Terry on the other forum, he should now.

judec · 01-28-2008, 11:40 AM

hmmm, OK, gonna steal some info from the other forum:

Quote:

Originally Posted by Terry Burger

Hey guys, I read a few people out there still don't believe that catless downpipes make big power gains. I figured I'd pull up a couple of charts to show exactly what I was able to gain from them.

Mods for the blue run: JB2R, 97 octane, drop in filter, catback

Changed for red run: Added Ultimate Racing catless downpipes & 1/2 psi of boost (aka hot pill)

Changed for green run: Reinstalled the stock catback system and 2nd cats, but added cone air filters and an additional 1/2 psi over the red runs.

So the addition of the downpipes and 1/2 psi was worth around 35rwhp. Pretty ridiculous gains, actually. Then adding the cone filters and another 1/2 psi upped the ante an additional 25rwhp.

I also noticed great gains on 91 octane with the downpipes + H pill, which is the second chart. Again ~25rwhp with DP + 1/2 psi of boost. Figure the DP alone would easily be 15rwhp, even at that lower power level.

Ultimate Racing · 01-28-2008, 12:19 PM

The runs are stock, hf catted, and catless in order of horsepower. Boost is marginally affected by the downpipes.

Darryl
www.ultimate-racing.com

nj335i · 01-28-2008, 12:34 PM

Quote:

Originally Posted by reb03

Good question. For emissions purposes I want UR catted DPs with stock exhaust but I'm not sure there will be any gains. Looking forward to the responses.

I haven't redynoed after installing my UR HFC DPs, but I definitely felt an increase in power. In addition, it help throttle response and you can hear the turbos spool more. I would recommend it! To me, it makes more sense to upgrade DPs first because it'll yield better results than a catback system. The UR HFC DPs are my only performance mods.

e90AW335i · 01-28-2008, 12:45 PM

Quote:

Originally Posted by nj335i

To me, it makes more sense to upgrade DPs first because it'll yield better results than a catback system.

+1, the stock dp's are the major restriction in the whole exhaust system. Even getting the high flow cats with bigger piping helps the turbos breath better...

01-26-2008, 10:59 PM	#1
cn555ic 469 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	DP or exhaust? I was wondering if you get DP with stock exhaust, would it be the same as getting a catback exhaust system and no DPs as far as HP is concerned?? Obviously getting both would be the most HP gained, but my question is, if either option used, which one would gain more HP. If you get DP the stock exhaust would restrict the flow at the end, but if you get exhaust with the stock DP's, I think it would produce less restriction towards the end!!! I would like to know what you guys think..
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01-26-2008, 11:10 PM	#2
oct1285 Captain 56 Rep 608 Posts Drives: Out of warranty Join Date: Dec 2006 Location: TX iTrader: (4)	well if you just installed dp's and no exhaust then I can't forsee any real hp gain but your turbos might spool up faster...maybe. And your throttle response might change too. Iono I'm basing this off of my past experience with a WRX
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01-26-2008, 11:22 PM	#3
NPDAN Colonel 101 Rep 2,572 Posts Drives: AW DCT M3 Join Date: Feb 2007 Location: So.Cal iTrader: (7) Garage List 2008 E92 M3 [8.00] 07' E92 335i [0.00]	how much different are after market downpipes than stock? __________________
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01-26-2008, 11:23 PM	#4
RetroGamerJP Lieutenant 58 Rep 401 Posts Drives: 2023 M3 Competition Join Date: Sep 2006 Location: Atlanta GA iTrader: (3)	I actually lost about 8 HP... with exhaust only... gained about the same in TQ though...
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01-27-2008, 12:02 AM	#5
stillclaimndp Dancing Machine 50 Rep 1,419 Posts Drives: 335i e90 ZSP Join Date: Aug 2007 Location: Walnut Creek, Ca iTrader: (0)	terry got A LOT of power with catless downpipes and stock exhaust... way more than he got out of just cat back... __________________ 2007 e90 & 1981 Corvette Predecessors: 2007 BMW 335i E92, 2006 M5, 2008 Viper SRT10 Coupe, 2005 Viper Yellow, 2006 Corvette Z51, 2009 Challenger SRT8, 2006 S4, 2001.5 Nogaro Blue S4, 2006 GTI w/ DSG, 06 Evo IX, 04 S4, 04 911x51, 03 Evo VIII, 98 Eclipse GSX, 96 GST, 92 Galant Vr-4, '70 Grand Prix Model J, '70 Nova, '68 Firebird
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01-27-2008, 12:04 AM	#6
RMRC Lieutenant 20 Rep 475 Posts Drives: 2011 E90 335d Join Date: Nov 2006 Location: West iTrader: (0)	Good question. For emissions purposes I want UR catted DPs with stock exhaust but I'm not sure there will be any gains. Looking forward to the responses.
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01-27-2008, 12:09 AM	#8
Supramano Lieutenant 39 Rep 509 Posts Drives: 1995 BMW M3, 2008 335xi Sedan Join Date: Oct 2007 Location: Long Island, NY iTrader: (1)	ive heard there are more gains to be had when putting dps before exhaust. Something to do with opening the restriction earlier is better than later. catless dps with stock exhaust will produce better gains than an aftermarket catbck exhuast(not just section 3 mufflers). I think the dps which are the primary cats cause the most restriction in the exhaust system. __________________ Manny : 2008 335xi sedan : SG, Terra, Alum, 6mt, SPP, PP, 162s Mods; Procede V4 \| Remus Quads \| UR catless dps \| H&R coilovers \| Modified CDV \| Injen Intake \| Spearco IC \| Forge DVs \| Defi Boost Gauge w/controller \| Vorsteiner CF Hood + Front Lip \| OEM M-tech Body kit \| Hamann eyelids \| Predator Ice Angels \| 19" Volk Progressive Me's \| Rotora BBK \| 18" Rota Torques w/Blizzaks
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01-27-2008, 12:13 AM	#9
bullmrkt Lieutenant 24 Rep 464 Posts Drives: 4 wheels Join Date: Feb 2007 Location: usually my desk iTrader: (0)	DP's first. __________________ 2021 AMG E63S Hammer Wagon 2002 BMW Z8 (with a Dinan DP Engine) 1996 Porsche 911 (993) Turbo 1995 Ferrari F355 Berlinetta 6mt 1964 Porsche 356 C Coupe
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01-27-2008, 01:44 AM	#12
Gen_E92 Brigadier General 121 Rep 3,430 Posts Drives: slow Join Date: Oct 2006 Location: Vancouver iTrader: (17) Garage List 2007 335i [7.80]	I would go with DP if I have a E93, makes more power than a cat-back and not much louder than stock. Just not a fan of loud verts unless it's exotic like Ferrari/Lambo etc.
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01-27-2008, 02:22 PM	#13
Sniz Lieutenant General 692 Rep 10,584 Posts Drives: e92 335 - gone // e36 M3 turbo Join Date: Mar 2007 Location: Ellicott City, MD iTrader: (1)	cn...i'm in the same situation. I'm thinking of running catless downpipes and the stock exhaust for awhile. If I do that, I'll eventually go with a custom exhaust w/ a high flow cat at the front. I dont want to be completely catless. __________________
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01-27-2008, 09:59 PM	#14
boosted305 Private First Class 7 Rep 115 Posts Drives: 335i Coupe Join Date: Nov 2007 Location: South Florida iTrader: (0)	interesting..... just curious... how does it sound with catless DP's and the stock exhaust?
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01-28-2008, 11:06 AM	#16
Ultimate Racing Lieutenant 28 Rep 469 Posts Drives: 335i, Evo VIII, WRX, STi, 350Z Join Date: Jan 2007 Location: Toronto, Canada iTrader: (2)	Everyone always seem to forget that our downpipe (catless and catted) dyno results are with stock catback! Darryl www.ultimate-racing.com
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01-28-2008, 11:19 AM	#18
judec born to be turbocharged 24 Rep 1,347 Posts Drives: Not a bimmer yet Join Date: May 2007 Location: Slovakia iTrader: (0)	nope, we dont, at least me not. No question DPs are beneficial. The question is how much are they restricted by stock catbacks under stock boost and how much when running tunes. Gonna ask Terry on the other forum, he should now. __________________ Disclaimer: All this message was written with recycled electrons.
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01-28-2008, 12:19 PM	#20
Ultimate Racing Lieutenant 28 Rep 469 Posts Drives: 335i, Evo VIII, WRX, STi, 350Z Join Date: Jan 2007 Location: Toronto, Canada iTrader: (2)	The runs are stock, hf catted, and catless in order of horsepower. Boost is marginally affected by the downpipes. Darryl www.ultimate-racing.com
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