I cant make up my mind on which one i want ? What at the pro's and con's on 2.5in like the title says...

 

2.5 Will obvously flow more than the stock pipes. It will also be able to accomidate higher overall HP.

You might lose some low end torque though, but not much. There really isn't much of a disadvantage.
Slightly worse gas milage maybe? ( like 0.5 MPG?)

 

I guess i mean more like noise wise ? and daily driver-ability wise if thats a word lol ? anywho...anybody who has a setup like this please tell me what your thoughts are ?

 

to be honest, you might not even notice the difference

if you're staying N/A, on a dyno the 2.25" might make better numbers but I'm willing to bet butt dynos will show no difference.

I've had both 2.25" exhaust and 2.5" exhaust (I have 2.5" right now) and the gains were so small from the exhaust period that its hard to even tell.

Its general knowledge though that 2.25" piping is supposed to provide the optimal flow on a small NA 4 cyl engine.

I would get whatever makes you happy...

I am wondering however, how 2.5" from the header back would effect me. I plan on purchasing a header, high flow cat and I'm not too sure what my downpipe size should be.

 

All depends on your speed, here in NM the highways are 75 but i usually travel at 90+ and at those speeds it drones but it not bad at all at 80 or less.

 

well shittier sound with 2.5 compared to the 2.25" and just depends on which company you trust.

 

Well i got the magnaflow style muffler with a tip on it now, and it sounds good, but it feels like it choked up on the top end, and i want it to be just a smidge louder so i suppose ill just go with the 2.25 since i aint got enough power to make use for the 2.5in!

 

if your going turbo in the future definately go 2.5"

 

youll kick yourself in the ass later if u dont go 2.5 inch

 

2.5" will accomodate the hp increase from any future mods you may make... if you're staying 2.25... just get a muffler on there and leave the rest...

 

gmpp exhaust is 2.25 and there is a lil increase in hp and torque plus it sounds really good.

 

i just got the stock muffler cut off and put a high flow muffler, not much difference but it sounds kool

 

I bought the DC Catback. its 2.25 i think. sounds nice and i can tell it incresed my HP as well. love it. + its stainlessteal. my stock exhaust pipe was rusted to **** allready. car isnt even 6 months old. i literly took a hack saw and did 3 motions and the pipe fell apart.

 

The DC is 2.5" also.... I have always found that cars 1.6-1.9 liter should stay around 2.25" and cars with larger generally do better with 2.5" just depends on the car and what future plans are... I plan on going turbo, so I am gonna do 2.5" for now!

 

dc is 2.25 not 2.5

 

that is correct

 

I didnt read the entire thread. SO somebody may have told you this already. BUT backpressure is your friend. You put too big of an exhaust on your car, and you wont see any gains. 800whp big blocks run great with 3 inch pipe...so 2 and a half could possibly be overkill for your application. Just a thought.

 

I agree completely, backpressure is a good thing. The compression on these things isn't necessarily through the roof.

 

I apologize... I was given some false info... the DC is in fact 2.25" pipe! My bad and sorry for the confusion!

 

has anyone managed to get a hold of the borla system yet?? I'm still on the waiting list @ Gravana, but the sooner I get the exhaust the sooner I put both the header and exhaust on...

 

if big blocks are running 3" exhaust its dual exhaust, not the same...

 

i love the people here who think they know more than gm's performance division.

 

Hey I'm about to put the 2.5 to the test at the end of the month, I'll let you know how it goes. Wish me luck.

 

The guys that did my exhaust told me that if you are NOT getting mandrel bent pipe with 2.5" it wont fit over the rear axle that you have to do 2.25" if it is crush bent??? Is that true I went with mandrel so it really doesn't matter but has anyone else heard that with their 2.2's?

 

that doesn't make sense to me at all...its smaller piping so it should have more clearance by that alone. And then in the method of bending the pipe should give u a little bit more space as well since they're pushin the pipe in towards the bend.