Midpipe's importance

[ThatOneThere]

Hello everyone,

It's been a year since I bought my BRZ and been driving it daily ever since. For the 1st year anniversary I made a upgrade plan. I don't really prioritize aesthetics over internals, so first thing on my list happens to be an Exhaust System.

I should note, that where I am from, the performance aftermarket part shops are non-existant, I order my parts from other countries.

I did a lot of research about going S/C route and modification in general so the couple of questions that I have are straight-forward:

1. I have a local guy selling used FT86 aftermarket parts he salvaged. I have 2 choices, Perrin axle back (No midpipe) or Invidia N1 catback (With midpipe). I find N1 sound to be obnoxious, but if the HP gains from midpipe and future-upgrade-proofing my exhaust system is worth it I could order silencers. Which one should I go for?

2. What about junction points of exhaust pipes? E.g. ACE Header -> Perrin overpipe? Are there any issues connecting such parts from different manufacturers?
Speaking of different manufacturers, anything to lose if one pipe diameter is 2.75" and the other is 3"? Are there specialized gaskets for connecting different diameters or just welding?

[p1l0t]

Originally Posted by ThatOneThere

Hello everyone,



It's been a year since I bought my BRZ and been driving it daily ever since. For the 1st year anniversary I made a upgrade plan. I don't really prioritize aesthetics over internals, so first thing on my list happens to be an Exhaust System.



I should note, that where I am from, the performance aftermarket part shops are non-existant, I order my parts from other countries.



I did a lot of research about going S/C route and modification in general so the couple of questions that I have are straight-forward:



1. I have a local guy selling used FT86 aftermarket parts he salvaged. I have 2 choices, Perrin axle back (No midpipe) or Invidia N1 catback (With midpipe). I find N1 sound to be obnoxious, but if the HP gains from midpipe and future-upgrade-proofing my exhaust system is worth it I could order silencers. Which one should I go for?



2. What about junction points of exhaust pipes? E.g. ACE Header -> Perrin overpipe? Are there any issues connecting such parts from different manufacturers?

Speaking of different manufacturers, anything to lose if one pipe diameter is 2.75" and the other is 3"? Are there specialized gaskets for connecting different diameters or just welding?

I have nothing between my headers and my muffler and it sounds pretty good. A little ricey..

Sent from my SM-G975U using Tapatalk

[SuperTom]

Originally Posted by ThatOneThere

Hello everyone,

It's been a year since I bought my BRZ and been driving it daily ever since. For the 1st year anniversary I made a upgrade plan. I don't really prioritize aesthetics over internals, so first thing on my list happens to be an Exhaust System.

I should note, that where I am from, the performance aftermarket part shops are non-existant, I order my parts from other countries.

I did a lot of research about going S/C route and modification in general so the couple of questions that I have are straight-forward:

1. I have a local guy selling used FT86 aftermarket parts he salvaged. I have 2 choices, Perrin axle back (No midpipe) or Invidia N1 catback (With midpipe). I find N1 sound to be obnoxious, but if the HP gains from midpipe and future-upgrade-proofing my exhaust system is worth it I could order silencers. Which one should I go for?

2. What about junction points of exhaust pipes? E.g. ACE Header -> Perrin overpipe? Are there any issues connecting such parts from different manufacturers?
Speaking of different manufacturers, anything to lose if one pipe diameter is 2.75" and the other is 3"? Are there specialized gaskets for connecting different diameters or just welding?

Ace headers have their own overpipe, you can't use anything else.

[ThatOneThere]

Originally Posted by SuperTom

Ace headers have their own overpipe, you can't use anything else.

That's good to know. Somehow I overlooked that, thanks!

[Ernest72]

Stock overpipe is fine. It adds no power changing it although being the smallest restriction. I have jdl catless headers, stock overpipe, jdl catted resonated front pipe and then invidia q300 carback. Car runs and sounds great.

I did hear that the ace header gets more power, there is a thread about it.

[RToyo86]

There are a bunch of threads that document that catbacks yield very little to no power gains. Go with the sound profile you want. If you want power, start at the header, then make changes as needed.

If you are going with ace header, stock catback or something as quiet as possible is probably more desirable.

[tomm.brz]

If you go FI, specially supercharged, a catback can become a restriction

A stock catback with restrictive midpipe and muffled axbleback can net you even 10whp less, compared to a bigger diameter/straight catback

NA form, yes.. you wouldnt notice the difference
but FI it makes a difference

[86MLR]

I made 270hpatw/280 nm (ran out of fuel) with a AVO turvo, 2.5" overpipe and 2.5" resonated catless frontpipe with the OEM catback.

NA I made 198hpatw with only a drop in and decatted OEM header, 2.5" overpipe, decatted front pipe and OEM cat back exhaust.

The biggest and best mod for power gains is actually finding a tuner, who actually knows what he is doing.

#pulseracing

D-4SFTW

My opinionated opinion is the 2 cats are the major restriction NA, if you can drop them your golden.

Disclaimer: I'm currently running a ARC GRiP catback because it was cheap and it sounds awesomeballs.

Did I mention I'm opinionated?????

[tomm.brz]

yes

but an oem catback is still a restriction for a FI car, no matter what

Cosworth declared that they dyno-measured a 10whp gain from an oem catback to a straight one, on a car with their SC, and it makes sense since exhaust restriction are a pain in the ass for a supercharged engine, more than for a turbo since the turbo itself is the biggest restriction

of course the cats are worse, but for a catless car, SC, a oem catback WILL worsen performance

[86MLR]

Originally Posted by tomm.brz

Cosworth declared that they dyno-measured a 10whp gain

Of course they did, they sell catbacks don't they.

[tomm.brz]

Originally Posted by 86MLR

Of course they did, they sell catbacks don't they.

Do they? i never heard of catback of cosworth for brz but i could be wrong... when i was talking to Coswortg about this they suggested me catbacks of other vendors actually

If you don't think a muffled catback isn t a restriction in a supercharged engine I don t know what to say to you, to me it is and it totaly makes sense

edit: yes they sell them. Still won t change my mind about it