Well, I'm doing all this research on the 3 inch exhaust and people are saying it's way cheaper to let the local muffler shop custom build a 3 inch exhaust.
So what I was gonna do is let them do a custom 3 inch exhaust from headers back and then get them to weld me a magnaflow tip or something on it.

Question:
Will it perform as well as an aftermarket 3 inch? I mean, it wouldn't be mandrel bent, but how much of a difference you guys think it would make??

 

There's really no need for 3" ... maybe if you're turbo'd. But even then, it's still debatable.

But more to the question, if there's a local shop you trust, there's no reason they couldn't make a full custom exhaust for you... and yes, it would probably be cheaper.

 

Well, I'm not turbo'd...YET. But, I do plan on getting it before i get my turbo. main reason:
Tuner isn't exactly accross town. it's a TRIP for me to tune, so i want to eliminate it as less as possible.

 

Get the turbo before getting a 3 inch exhaust. Your car will be loud as hell without it.

 

Loud and lacking low end TQ like a civic...

 

I don't think you need 3", even with a turbo, but whatever you want to do,

on the other question, I've had most of my exhaust's done by a local shop, regardless of the vehicle, I prefer to see whats going on under the car and have something made specific, I'm sure bolt-on stuff works fine, but I've always had good results having stuff made for me, a good shop will have a selection of mufflers, pipes, tips(depending on the vehicle) etc. gives a lot more options, imo

 

don't do it UNTIL you get a turbo, everyone always says they'll turbo and never do. 2.25 is all you really need, 2.5 if you want as well, but anything more is a waste.

 

turbo then exh.
:-)
3" exh is useless otherwise

 

I agree with everyone so far. And if your going to go ahead and do it dont go cheap and have crush bent pipes. Find someone who will do Mandrel bends. I know alot of people say you dont even need it with the turbo kits out for our cars but I just had a custom 3 inch made for my car and it seems to love it! Sounds amazing with the turbo. Without a turbo I'd bet it sounds like crap though.

 

running a 3in exhaust with no turbo is gonna be a nightmare starting up from red lights....aka no low end torque. i had my exhaust done at a custom shop. much cheaper than buying whatever full catback/axleback systems that are out there now. only draw back to my custom exhaust was that the piping did not have a chrome finish. but who sees the underside of your car anyways?

 

All good replies here - so many people still think bigger is better.

2.25" is all you need for N/A. If you're sure you'll be going turbo, move up to 2.5". Dezod sells 300hp turbos and he recommends only a 2.5" exhaust.

Here's what happens when you go 3" on just the axleback:

https://www.scionlife.com/forums/viewtopic.php?t=147111

 

LOL You mean that the tC is not 2.5" stock? Why would anyone downgrade to 2.25"!

 

here we go again...

because the tc's 2.43" stock exhaust has 2 cats(yeah kitties) and a huge chambered muffler creating quite a bit of restrictive back pressure.

once you remove the cats(you know stirfry)and the huge chambered muffler and get a straight through 2.5 exhaust system with a header you no longer have that back pressure
and lose quite a bit of low end TQ...

so whats the answer OTHER that getting a highflow cat and chambered muffler and shooting your self in the foot?

you "down grade" to 2.25inch you get to keep the straight through performance of your new exhaust and the smaller pipe diameter keeps sound levels down and you get to keep most if not all of your low end TQ.
this does not apply to F/I only NA.

as far as 3" pipe...i can see it if your turbo set up is putting down 280hp +
but below that i think "true" 2.5 is fine.

 

You're on point on just about everything except stock piping. I don't want this to become like the other thread, but I don't think you understand my point. It doesn't matter what the opening of any piece of our exhaust is. What matters is the inner diameter for the majority of the piping. Although the opening on the s-pipe may be 2.5" it bottlenecks at 2" (which you said your self). Then even if the opening is 2.41" or what not in the mid-pipe, after the cat and the resonator it becomes narrow again to about 2.25". I never said it was consistent straight through exhaust, but on average it would not flow as a 2.5", 2.41", or even 60mm would, even if you were to take out the cat on the mid-pipe. It may appear to have those diameters at different points, but it can only flow at the rate of the narrower piping which is very close to 2.25" I/D if not less. That's why the Magnaflow gives you 6-7HP as oppsed to only an axle back which can yield maybe 2-3. The magnaflow replaces the piping after the cat to 2.25". Where as the best axle backs retain the stock mid-pipe.

Also, even 2.25" is more than adequate, civics and most other 4 bangers come with 2" exhausts.

 

I'm down with that, I guess you could say the ever changing pipe diameter and 2 cats and the large chambered muffler is what kills the top end in of the tc's stock exhaust.

believe or not our stock MID-pipe isn't all that bad, its the header,S-pipe and axleback that really kill performance at high rpms.

 

Agreed...

 

well i actually did a three and it was horrid. loud as f*** and the stock felt better.

 

Because you most likely neglected to slap on a resonator and/or a cat on that 3" pipe. Let me guess, the ZPI one?

 

Not to be a *****, but a 3" exhaust on a NA stock or bolt on tc is just silly on every level...just to even consider it.

even a set up of an Invidia 2.5 and tsudo N1 2.5 catless cat back is not "TRUE" 2.5 if you really think about it...and you lose plenty of low end TQ as it is...

 

True, but back pressure has nothing to do with his exhaust sounding bad. If he would have put a 2.5" without a cat and/or resonator it would have sounded just as bad and raspy, though with a different tone.