[turb0mik3]

Hello All,

I rarely post questions because I do a lot of research but even Fred from ER and HPF are stumped and really don't have a clear answer...

As all of you know, I track my car and it has become more of a weekend/track/show car.

So my questions to all of you is the follow...

1) I have been thinking about exhaust and was wondering if anyone has done a dyno comparison between a FBO 335i w/ mufflers vs a FBO 335i w/ straight pipes (including DPs). I can only imagine the gains would be kind of minimal, but curious nonetheless.

The reason I ask is because I might have a "test pipe" catless exhaust for the track. I spoke with Fred and might want to do a catless pipe sraight back through the middle of the car and out the back middle with a dual pipe look like the studie and BMW race cars. I would of course work around the differential.

2) For the above idea, we can either have a single tube (4-4.5") like the HPF exhaust or a dual straight pipe setup that comes to one in at the very end (probably AXLE back). Do any of you think that the single 4-4.5" would be better flowing than a dual 2.5 setup? Would the 4-4.5" also be lighter?

I know this is confusing, but I am thinking of a way to cut weight (without mufflers) and open up the exhaust system in the most straight through design possible.

Thanks and hopefully I can get some good input!

[utfenix335i]

Give me a few weeks and Ill let you know. I'm thinking about doing this myself. I'm not FBO, but pretty close to it.

[creaminz]

Oh wha!?

[tibra1]

With that beast you have I would just run downpipes..the weight savings alone would be significant..

[ETS Michael]

I have step by step upgrades here, but with downpipes last instead of before exhaust. This may help.

http://www.extremeturbosystems.com/E...p-Dyno-Sheets/

[NiVeDh]

Originally Posted by creaminz

Oh wha!?

[DefactoM6]

Fitting a 4.5" round single and keeping everything under the car intact will be an absolute pig...I think that alone forces your hand. You could go oval, but that's even bigger $$$ than the $$$ of 4.5. The other thing is that 4.5" is just comically huge given our pea shooter turbos.

If you want to cut weight, reduce backpressure, and look different, just do a side exit exhaust.

[turb0mik3]

Originally Posted by creaminz

Oh wha!?

DAMN!!!! That looks soooo dope.

Originally Posted by tibra1

With that beast you have I would just run downpipes..the weight savings alone would be significant..

Ya, I don't think I could get away with open downpipes. I want it to at least make it look like I have some sort of downpipe/cat on the car, ha.

Originally Posted by ETS Michael

I have step by step upgrades here, but with downpipes last instead of before exhaust. This may help.

http://www.extremeturbosystems.com/E...p-Dyno-Sheets/

I would like to see the dyno without the ets exhaust on if you could do that! lol.

Originally Posted by DefactoM6

Fitting a 4.5" round single and keeping everything under the car intact will be an absolute pig...I think that alone forces your hand. You could go oval, but that's even bigger $$$ than the $$$ of 4.5. The other thing is that 4.5" is just comically huge given our pea shooter turbos.

If you want to cut weight, reduce backpressure, and look different, just do a side exit exhaust.

Out the side is an interesting idea. Never really thought about that. I'll take a look to see if that is even possible!