Does the overpipe really make a difference?
 

I'm looking at getting the Perrin exhaust system and I'm weighing up whether to get it with the over pipe, or to just get the catted front pipe and the cat back components.

My question is, does the overpipe really do anything? Perrin quotes a 3rwhp gain but that's pretty negligible on a dyno and wouldn't even be noticed when driving. How does it increase flow being such a small part of the system?

Does anyone have any experience comparing these two setups?

the stock one is 2.16" and has some bumps and dents in it. its probably the biggest restriction in the exhaust system as far as piping goes. the overpipe is definitely worth it! there are a few threads about it already just do a search.

absolutely... nameless has an incredible op?downpipe combo piece that I am strongly considering. What it does is combine the two exhaust pieces together and reduce some of the arc or degress that the op into the downpipe with otherwise create stock.. this improves flow and increases power.

the op is so damn close to the headers.. improving this piece will absolutely create power power than say changing your muffler or midpipe.

It won't add you even 2 hp. Not worth to spend money on snake oil. If you want to mod exhaust, you have to go with high flow cat or just straight pipe. Though it wont be streat legal in most states.

Im in the same boat. I PM'd Nameless and they said it will make a difference but when i PM'd FA20Club about theirs they said no not really, don't worry about it until you do headers. Im currently waiting on JDL to see what they say about it.

Haha thanks for the responses guys. Seems like opinions are divided here.

I wasn't planning on doing headers for awhile. My initial plan was just to do Header back + intake + tune.

dood,
i am not sure what you have on your car or what your planning to purchase 1st but its a waste of your efforts, money and time to just get an OP alone

either do a header/OP combo or the nameless OP/downpipe combo and headers later. this will get you a bang for your buck.. if you do just the headers alone (no OP) your still going to get nice gains but your choking the flow with a stock OP

while the OP is a crucial part of the exhaust system.. being so close to the engine and an intriquite piece.. it accounts for like 8% of the length of the entire exhaust piece and is nothing more than a single flow pipe.

Skip the intake. Here is what I would do in this order:

Tune
Header
Exhaust(sound purposes only)

Everything else can stay stock. The front and overpipe won't get you much.

I've already got a Takeda Intake installed on the car.

So do you think Perrin Cat Back + Borla UEL headers would be a better option than just Perrin Header Back?

I want to keep at least one of the cats in the car and not be too loud. I was thinking of getting the resonated catback.

Its a good idea and common plan but then you have to deal w/ the repercussions of the CEL.

Start on the engine side of your exhaust and work backwards. Muffler is mostly for sound change but doing headers and/or OP/FP will change your sound anyway.

Plus a tune to maximize benefits and fix torque dip/cel if you can.

Is the cel a prevalent issue with changing the headers or is it only isolated cases?

Get the revworks. Better quality. I would get the tune first before you get the header. Tune is what will unlock the most from any header. Also it will help and disable the CEL from removing the cat in the header where the main O2 senzors are. Keep the stock front pipe with the cat.

Yes. Headers first. Then over pipe. Then front pipe. Then catback.

The ideal thing would be to do it all at once and tune right then. That way you're not driving around with all this without a tune, or trying to tune your stock car before you get all this stuff.

Get the revworks. Better quality. I would get the tune first before you get the header. Tune is what will unlock the most from any header. Keep the stock front pipe with the cat.

NO.

I have heard some fitment issues with overpipes. I would just leave them alone just because of that. 2whp is not worth having an annoying rubbing sound every time you drive. Just save the 200 - 300 bucks for some good headers.

Agree with above. Seems more (potential) headache than it's worth. The stock OP also has heat shielding which the aftermarket ones don't have, though you can order some of them with ceramic coating.

"Does the overpipe really make a difference?"

Of course it does. Possibly as much as +3 whp with a tune. The real question is if +3 whp is worth $300. To some it is, to others it is not.

The Private Label MFG over pipe is 35% lighter than stock. SOLD! If I get any power out of it, that's just a fun little side effect. Different strokes...

Yes, but you can always get a spacer/defouler or whatever you call them until you can get a tune.

I personally got the Op/FP combo from nameless and my headers will arrive within a week or so. That's all I'm doing for my exhaust, doing that alone will change the sound enough for me. I'm kind of waiting on people to figure out some of the up and coming tuning solutions before I decide on one, until then I'll be using a spacer.

Some people will swear against spacers as well but it seems like enough people on here have had enough success with them anyway.

Yes, it makes a difference. I just attached a 3" downpipe/overpipe to the stock header and feel the difference in flow. The stock header is a piece of crap though. I'll be replacing it once my JDL arrives.

I just installed a Borla UEL headers on all stock exhaust. Sounds good and still no CEL. I do have a tune though, but I haven't gotten my tune updated to take my headers into account. @FA20Club.com provided my tune for my Automatic BRZ, it has been running great. I will be sending logs to them to have them update my tune for Borla headers.

My next mod is coming in the mail, (works axle back muffler). After that, i will keep an eye out for a a good qulaity used/new overpipe that is selling less than $200 shipped.

My advise to the O.P. would be as follows ; tune->headers->overpipe->axleback or cat back.

The tune, license & cable would be as much as a perrin catback BUT the catback won't yield you as much "ass kicking" as the tune will. Follow that with headers, and now you have a nice increase in power and sound. An overpipe will increase the sound and exhaust flow as well, but this is stricktly preference as stated by many before me.

If you want loud muffler noise, then go with an axleback/catback. The headers will definitely increase sound volume.

including myself many people think "worth to get OP?"
for me, i cant think myself to spend $300+ to get OP. I just spent money on Motiv Catless FP and recently got nameless axle back. (waiting for shipment)
if i get header, yes i would get OP as well

I've said this in other threads, technically the nameless OP is only $100, since the FP is $400 and the combo is $500. If you think about it that way it's not so bad is it?

The crossover pipe makes a big difference in turbo FI applications, however. ;)

FP is only $100, since the OP is $400 and combo is $500.
if you think about it that way it's so expensive isnt it? :happyanim:

I am just messing with ya. :lol:

If you're going to replace OP and the header, do them at the same time. Swapping the OP typically requires lifting the engine up a bit, so might as well do it once when you're connecting the header to the OP anyway.

Some vendors have said most of the gains are had at the front/overpipe. Just look at the Nameless Axle Back and Front/Over pipe combo. They said the mid pipe didnt get any gains when they did their R&D. I dont think it would be any different for any other systems. If I just bought my car I would do it in this order

Tune
Front/Over Pipe
Nameless Axle Back
Header
Perrin Silicone Tube/CAI or Drop In Filter/Perrin Silicone Tube/HKS Intake Duct
Mid Pipe for peace of mind and just to complete the whole system

I thought(or heard) the major gain is from header, isn't it?


Thanks.

Tune + Header -> Overpipe + Front pipe > Drop-in/CAI > (Pick your flavor of catback). That's the best N/A performance and the order it goes in but they all work together even better when they are tuned together.

As a side note, in order to install the overpipe, you will need to drop the header, so you might as well grab one of those while you are at it. You should at LEAST grab a new header gasket.

I installed my Perrin OP without dropping the header or lifting the engine. I did have to remove the stock head shields first though. Then it was a simple matter of snaking the stock OP through and the aftermarket one back in.

I didn't touch the header either. First I loosened the front pipe by dropping it off that bracket that's towards the rear of the front pipe. Then I took the shielding off the factory over pipe, completed the puzzle of getting it out, and puzzled the new one back in. No clearance issues or rattling. And I have USED Borla headers. People talk so much shit about them, but I've had zero problems in the 300 miles or so I've driven with them. PLM over pipe is doing just fine too. No CELs. Haven't even flashed with my OpenFlash Tablet yet.

Oh and the PLM over pipe came with two nice gaskets, so didn't have to reuse any of the oldness.

if power is the primary concern i would just buy the largest diameter exhaust you can and plan to go FI in the future. you're pissin' in the wind trying to make real power NA.

if you don't plan on going FI then which brand of exhaust you buy, which components etc will have little impact on performance, good or bad. the gains to be had are within the margin of error. we're talking single-digit HP gains here, maybe teens with a tune.

as always the amount of power you make, and how consistently you make it, has more to do with your tune than anything else.

i'll note that i saw only minor gains with my turbo setup replacing the exhaust until the final piece was in place, then it was night and day. the whole thing had to be upgraded before the gains were even noticeable.

^ this, FI or E85 + tune makes the biggest difference, header helps with the dip and maybe a little on the curve but best bang for the buck aside from FI is E85 + a good tune if you have E85 conveniently vailable to you.

I TRIED to remove the heatshield, but the last bolt was heavily rusted AND hard to reach. Gave up and raised the engine and the OP just dropped out.

It is fairly simple to manage CEL with no tune. $20 o2 spacer from Ft86speedfactory.com , a $5 app on iPhone or $15-$20 torque app on android, $25-30 on one of those Bluetooth receiver things that plug into your car so you can clear codes.

Yes but the power comes mostly from the tune....

For your health.