Yes. With the stock turbo and tune, an aftermarket DP nets you just about zero gain. With a protune you might get a little extra power, but if you were to change out your DP, you must change out the O2 housing as well to see the maximum gain.

If you were planning on getting a protune in the near future, yes waiting would be a good idea until you have made all your mods first (HFC, DP & O2 housing, CBE).

On the other hand if you have a Cobb AP, why wait? You would see a good gain with just the HFC and CBE (Stage 1 or 2 tune).

 

holy crap man this is a 2 year old thread!

 

Just to add... I've had the stock O2 housing off the car 2 times now, and I can definitively say that there's not much to gain there. A couple of WHP at most... and only at the point where it connects to the down pipe. If that opening is enlarged, that flow restriction could be reduced, but the bellmouth itself cannot be improved much.

People who tout the O2 housing-combination downpipes obviously haven't taken a good look at the stock O2 housing with their own eyes; it's a HUGE improvement over the Evo VIII/IX O2 housing!

 

Absolutely!

 

I keep reading how the o2 housing+downpipe combo is worth power but just the downpipe isn't yet I have yet to see any dyno proof of this. Another common theme is that you will see power from the o2 housing+downpipe combo on a larger turbo but i haven't seen any dyno proof of that either.

i really wish someone would just end this speculation and post up some same day before and after dyno runs with the only change being the o2 housing and downpipe combo on a stock and on a larger turbo.

because right now, i'm really not seeing the point to buying anything beyond Perrin's TBE setup.

 

The problem is the cost of dyno time for the average consumer. It would be nice to see a vendor actually do a back to back swap with the correct stuff being logged; boost, AFRs, everything.

It'd also be nice if I had a pony.

 

definitely the problem since the cost of labor alone is a lot on the o2 housing/downpipe.

hey AMS, etc....you're up to bat. prove your part.

just do a few runs of a car with a catback and test pipe(or hfc pipe) with the stock 02 housing and downpipe and a few runs with your o2 housing/downpipe installed as the only change.

heck if you want to tune between the two part changes to try to eek out more power, go for it.

just want to see this difference...on a stock turbo or on an aftermarket one.

 

The gains really wouldn't be conclusive... a few WHP at most - within the margin of error of any dyno.

Point is: there are many, many more worth-while modifications. I ported my entire exhaust manifold but didn't touch the O2 housing because it seems optimal from the factory. It's certainly not limiting my CBRD BB-X - holds 30 psi to 7600 rpm just fine!

 

PERFECT! Thank you for that, that is the exact turbo I will be buying for my car.

Perrin TBE it is!

 

Yeah, it doesn't seem to be a big limitation, and you're probably right; it'll be within the margin of error.

Cheap enough part though, and a good time to change it is during the turbo swap, so I'll probably end up with mine changed out too.

 

well it was a real b*tch getting my DP on... so it's not coming back off gains or not lol.

 

thats interesting does the sound of the exhaust sound any different or the same still what about the length of time the turbo takes to spool or does it not change anything

 

I would be willing to bet your 30psi would be lower at redline if you changed out your 02/downpipe, reason being your engine would be flowing more efficiently. So you would probably make the same power on lower psi and could lower your WGDC's. It is similar to cams, usually peak boost drops when you add cams because your engine flows better, since boost is a measure of restriction (air not getting into the engine).

 

That makes no sense since the O2 housing and downpipe are post-turbo restrictions. Making them higher-flowing would allow the same turbo on the same engine to produce more boost efficiently since the turbine wheel would be under less back-pressure on the exit side.

Same goes for replacing your exhaust with a high-flowing cat-back exhaust. It will decrease spool time and cause your boost to actually increase.

Eliminating intake restrictions and increasing internal engine efficiency would cause the effect you describe.

Trust me, I've been through countless iterations of exhaust systems on my other turbo car. Less post-turbo exhaust restriction = more boost. You're right about the required WGDC, however. But it's intake restriction that regulates boost pressure, not exhaust restriction.

 

wow thats really nice to know [= no need for a aftermarket dp then , more money for other mods