Gentlemen (and ladies too I guess),
I am sending my car to CMS in a couple of weeks. Now I am going to order the last couple of parts on Monday. I am going to be doing LPP LTs, TD, Xpipe, over the axel, double muffler. Any good reason to do 3" vs 2.5"? I am thinking 2.5" for the better clearance, but is there any real difference? I have a 95 Z28 at stock height. I just want to make sure that I don't have a lot of scraping going on. Is there a brand of muffler to stay away from? Keep in mind, this car is not going to be a monster, I plan on stopping around 400 RWHP, so there is not going to be a big turbo or anything crazy in it. She is going to turn into a weekend cruiser that occasionally makes an appearance at the track. She is mostly looks.
All I have to do is order the mufflers and the panhard bar replacement kit and off she goes to CMS, so please roger up here about size.

 

I'm not an expert mind you, but I think for your setup 2.5 would be enough. Yet if you think you MIGHT plan to go for more power in the future, might as well just do 3".

My initials are CMS... You're giving me you're car?

 

2.5 will be more than enough.

 

I'd run 3", it's what aftermarket replaces the stock exhaust with right? (my slp's are 3" atleast) you don't wanna run the same as a mustangs exhaust do you!? haha jk, but in all seriousness i'd run 3" especially if you're going to be running up to 400rwhp.

 

Do you find that a 2.5 is too restrictive? What about ground clearance?

 

So what the one guy here did, even though it's a bit expensive, and run the oval exhaust.

 

I am pushing the top of my budget for this project right now. I thought about oval piping, but I do not want to spend that cash. Maybe in the future on a project car when I am balling.

 

I think if you keep it at stock height you'll be fine either way, but, now that I think about it, 2.5's probably wouldn't be restrictive. I'm going to be running h/c/i with LPP into o/r Y pipe 3 inch all the way through. Yours will flow a hell of alot better than mine with 2.5..Basically you can't go wrong in my opinion..haha sorry to "flip flop"

 

what about the fact that I am not running any cats in it? Do I want something a little smaller in hopes of some kind of back pressure? I am also going to be running single chamber mufflers and an x pipe.

 

Dual 2.5 is not going to be restrictive, do some research. 3" is overkill

 

(I didn't vote by the way haha) With TD setup. Go 2.5 the chambered mufflers should help with lil back pressure, smaller pipes too, and will probably be more friendly to your funding, good luck with whatever you decide man.

 

ok, I did do some research before I posted this topic.... I was getting conflicting answers. As far as 2.5 being "restrictive" I was talking in comparison to the 3", and was not sure if it was needed. What are the pro/cons of each size, considering what I am looking at getting out of this car. I think a decent sized cam will be one of the last "big" things I do to this car.

 

Well obviously 3" has the capacity to allow more flow but it is just not necessary on most street vehicles. I ran a SINGLE 3" in the past with a cutout and only picked up 7hp with the cutout open, and this was with a Magnaflow catback.

 

2.5" should be more than sufficient for your goals. A good single 3" cat back would suffice aswell for a 400rwhp.

 

2.5" I don't gain anything worthwhile uncorking the 2.5" under my car. X-pipe to Dynomax Ultraflo mufflers and glasspack resonators tucked up in the quarterpanels make it pretty quiet for the performance.

Some guys swear I have to be wrong and best I can guess is maybe the ball and socket fitting on the headers and hookup pipes ar more choke than the 2.5" system.

 

My 2.5 inch duals have better ground clearence than my 3 inch y pipe.

 

My 3" true duals have more ground clearance than my 3" Y pipe and catback.


Yes, that's right. I do have 3" duals. Overkill on my car.

 

i am dropped two inches and my 3 inch system is extremely low..its hard to get a regular jack under the rear end to jack it up....so do think about what your gonna do as far as the height etc...mine is purely a toy and gets driven once every two months or so, so its not a big deal

 

2.5" is all you need. even for a 383 or something more. my friend has a destroked 454 and runs duel 2.5" and like you said youll get more ground clearance

 

looks like 2.5" it is... unless someone can come up with a good reason not too.

Also noticed almost no one is voting... oh well.