[E90ice]

I know some of you have stock catless DP's? Do you feel a difference? Is it worth it?

I was thinking about the catless map that Shiv is supposed to have for us...might work well with catless stock DP's.

Any thoughts?

[youngbuck]

I believe your best bet would be some Riss DP's. I wouldn't want to ruin the stock ones since you will need to service, and test emmisions.

Best,
YB

[shyestsparks]

+1, it's gonna be cheaper to buy an aftermarket catless DP than gutting the stock ones because you will eventually need your stock DPs.

[rideelement247]

On the other hand, the DPs will look stock if you get them gutted. Or you could just get the cat cut off and a piece of pipe welding in there just as cheap.

[E90ice]

Originally Posted by shyestsparks

+1, it's gonna be cheaper to buy an aftermarket catless DP than gutting the stock ones because you will eventually need your stock DPs.

How can it be cheaper to buy aftermarket, when they cost $1000? Gutting the stock ones costs $100.

[E90ice]

Originally Posted by youngbuck

I believe your best bet would be some Riss DP's. I wouldn't want to ruin the stock ones since you will need to service, and test emmisions.

Best,
YB

Well, if you ordered the catless ones...you're in the same shit.

[O-cha]

I think riss said it best on "the other site"

Originally Posted by o-cha

Not to smart to ripped out the cats from your stock pipes. It will cost you $2,000 when something comes up and you need them back to normal.

Originally Posted by riss

+1.

"I know its hard for me to respond to this since, well, we do make downpipes. I will give you honest feedback on gutted cats. The stock downpipes on the car taper under 2 inches at one point. Which basically means, both pipes start their flow at 2 inches. Please look at the top of the downpipes, turbo flange area. Immediately, the stock downpipes go from 3 inches to under 2 inches with a hard 90 degree bend. After gutting the cats, the downpipes will flow to about 3 inches where the cat honeycombs used to be. After that, it will flow to about 2 inches again, and go out to a 2.5 inch flange. The flow characteristics on the stock downpipes are absolutely horrible. Also, the stock downpipes cost about $1,600.00. Also, you can do a search on WALKED U's car. He actually gutted his stock cats as well, with an aftermarket catback system. He posted some videos/sound clips so you can hear what it sounds like. He really hated the sound of them and went catted downpipes instead. To really optimize power, for the long haul, get some catless downpipes or catted downpipes with mandrel bends so the flow goes all the way back. The stock catback system is pretty decent except for the crushes near the back. That's why aftermarket catback systems don't make as much power as downpipes, but it definitely helps. Hope this information helps."

[e90AW335i]

+1, What O-cha said.

[E90ice]

Interesting...thanks.

[fast_lap28]

so let me understand this clearly if I was to decide and go with new exhaust setup after I Dinan flash her...

1 - gutting your stock secondary cats is a NO NO regardless of aftermarket exhaust you put in or if you plan a custom setup? or if flash or piggyback installed...

2 - our stock exhaust works just fine EXCEPT the bends towards the mufflers? So keeping it OEM w/o 2nd cats is alright? I hate the bends

3 - best solution is to go with aftermarket DP's or catted DP's (UR or Riss) + OEM exhaust? Or is aftermarket setup with mendral bends + 2nd cat delete still the BEST solution for flow capabilities?

I am just at a crossroads, I WANT to achieve higher (exit) flow capabilities from the TT's and reduce the weight from the OEM system. Horsepower gains (although welcomed) is not what I am after, simply want the engine/turbos to breath better and release exhaust gases better.

I just can't mess with emissions issues or error codes here in NC cause the laws for passing inspection are freakin ridiculous!! so primary cats stay, I can't do JUST downpipes....

The maximum flow of the exhaust gases is what I really want to achieve after all is said and done, just not sure if messing with cats or not is really necessary after all

Any suggestions especially from those with Dinan is appreciated.

[Dan335i]

What about high flow catted down pipes,and a cat- back exhaust without the secondary cats?

[O-cha]

Why did this get moved out of FI, I mean I know this says "exhaust modifications" but this is purely a FI discussion.

[shyestsparks]

Originally Posted by E90ice

How can it be cheaper to buy aftermarket, when they cost $1000? Gutting the stock ones costs $100.

Cattless DPs are 599 at UR (Riss I don't know); What are you gonna do when it's time to smog the car if you decide to keep it in the long run or when you trade it in at the dealer? New OEM DPs are like 1300-1600.00 depending on the dealer.

[uberschnell]

Originally Posted by Dan335i

What about high flow catted down pipes,and a cat- back exhaust without the secondary cats?

Emissions standards are only going to get tougher. Soon that may not be enough to pass.

[AWD Addict]

When it was time to smog on my catless WRX, I used a little O2 simulator that told the ECU everything was okay.

Great little mod.

[E90ice]

Originally Posted by shyestsparks

Cattless DPs are 599 at UR (Riss I don't know); What are you gonna do when it's time to smog the car if you decide to keep it in the long run or when you trade it in at the dealer? New OEM DPs are like 1300-1600.00 depending on the dealer.

You just weld the cats back on.

[shyestsparks]

Originally Posted by E90ice

You just weld the cats back on.

Lol, Oh Ok, I thought that when you said gutting, you meant to literally "gut" your stock cats by taking all the inside materials out so it still looks like stock even though its not; so you were gonna "cut" the stock cats and weld straight pipes.
My bad, well in that case yeah, it's cheaper todo that.

[O-cha]

Originally Posted by shyestsparks

Lol, Oh Ok, I thought that when you said gutting, you meant to literally "gut" your stock cats by taking all the inside materials out so it still looks like stock even though its not; so you were gonna "cut" the stock cats and weld straight pipes.
My bad, well in that case yeah, it's cheaper todo that.

That was what he was talking about. Trying to save face for the lose.

[shyestsparks]

Originally Posted by O-cha

That was what he was talking about. Trying to save face for the lose.

I wasn't trying to win or lose, just trying to state my opinion; and I'm one who would admit something if I'm wrong, I don't have a problem with that, it's not like you're gonna be less of a man if you are wrong on something; in fact it takes a man to admit when he is wrong. Unfortunately I can't say that for certain individuals on this forum, and I'll leave it at that.

[O-cha]

Not talking about you.

[AWD Addict]

Stock downpipes may cost $2000 new, but who the hell would put brand new exhaust back on the car?

$150 on ebay.

http://cgi.ebay.com/ebaymotors/BMW-E...spagenameZWDVW