Does anyone know the size of the piping for these two? I want to get the GMPP cat back but if its smaller diameter then stock whats the point? I have a friend who owns a muffler shop and can custom build me anything I want. The price from him is about the same as the GMPP so I'm trying to figure out whats gonna be the best and give me the best gains.

Any help would be awesome! Thanks!

 

i believe there both 2.5"

 

Its all about Flow and back pressure, not always the size of the pipes

 

Im pretty damn sure the stock SS is 2.25" from the cat back, but the GMPP is 2.5"

 

Yeah i got the GMPP comin in the Mail and i know its 2.5, not sure about stock but 2.25 sounds about right

 

the stock is 2.5 and the gmpp is 2.25...

edit... sorry i thought it was the 2.0, im not positive but i think the 2.4 is 2.25

 

i measured mine today, and it was 2.25, cause i have heard many things, and i was curious as well, and it is infact 2.25

 

GMPP or Stock

 

stock

 

Ok so stock IS 2.25 and the GMPP IS 2.5. Thats what I was hoping. Guess I'll be ordering mine in a couple days to a week.

 

GMPP is 2.25

 

So they're BOTH 2.25?

Now I'm confused!

 

YES they are both 2.25", the GMPP will still be an upgrade in performance, dont have a muffler shop piece together a catback unless they have a mandrel bender, or else it would be a loss in perf...

 

just buy it, it'll have gains....

 

THANKS! And he does btw What you think? 2.5 inch cat back or stick with the GMPP one?

LMAO!! Thanks DOC!

 

I would personally buy the GMPP, I have had my catback pieced together and to tell you the truth you will end up spending more money b/c there is always going to be problems, so I would just buy the GMPP and be done w/ it, there wont be any fitment issues or anything and the GMPP is made to give you maximum perf throughout the powerband. With going w/ a bigger exhaust piping diameter you will loose some of your bottom end and gain it up top. I regret piecing my catback together b/c it is always one thing after another. Theres my opinion so just order it.....NOW!

 

I am trying to decide what to do for an exhaust too and am leaning toward the GMPP sport. Fitment, price, and warranty are issues which the GMPP addresses and there have been dyno-proven gains in HP, although they are not a ton alone (approx 5hp). Of course other mods will play off of the decreased resistance as you already know and I really like the sound. Also, the 2.25" piping of the stock unit is crush bent in many places and gets especially smaller over the axle whereas the GMPP does not. The GMPP is proven to flow better even though the pipe diameter is still 2.25", probably due to the use of a different muffler. My opinion is that the GMPP is a good choice if you aren't going past Stage 2 horsepower-wise (approx 240whp). However, if any setup requires you to put in the 60lb injectors, the GMPP will probably be the weak link and you should step up to a 2.5".

 

The dyno results I've seen from the GMPP show gains around 10 to 15 hp not sure where you got that 5 hp figure from. I'm also a 2.4SS which is N/A so I'm not worried about stage kits just getting the most out of my 2.4 is all.

 

I know the Magnaflow is in fact 2.5

 

the GMPP exhaust is 2 1/4" ... mine just came in on friday ... and the performance muffler is much smaller than stock ... im getting my GMPP exhaust manifold next month so im waithin to get them both installed at the same time....

 

Yeah, the results I've seen have been between 5 and 10whp but I am just trying to be conservative. However, maybe some saw larger gains that I don't know about. Also, I just used the stage 2 kit hp level as a gauge, since that's as far as I am planning on going, of when I think the exhaust becomes too restrictive. Its just my opinion but if you are planning on pushing your 2.4L past 230-240 crank hp or so you should probably look at something bigger. Just my two cents.

 

If I can get my 2.4 to the 200 HP mark I'll be happy as a pig in poop! LMAO! 240 at the the crank! Your a funny guy! But thanks anyway man. I don't expect anything near that not unles I do a cam swap and spray on it, neither are on my list of things to do.

And its always better to figure conservativly then overboard your right about that.

Thanks Eric! I'm ordering mine in about a week. I wonder why the touring is more then the sport tho? Makes no sence to me.

 

Look, the piping might be smaller but it flows more than the stock exhaust. Any cat-back will have a warranty and even if something went wrong, GM will have a very hard time proving that an aftermarket cat-back caused anything to the rest of your car. The cars now have ~240 crank horsepower...My personal setup....I have a ZZP header, ZZP 3" downpipe with a hi-flow cat and the GMPP cat-back and I have no issues with power. I am well over 240whp too (not crank..wheel horsepower). I have noticed that I have more torque with vehicles equipped with a larger exhaust setup. The 2.4l cars will benefit from the GMPP exhaust since it is higher flowing. I doubt that anything bigger will be of benefit until they are well above 250whp and/or fi'd.

 

I am glad to hear that the GMPP is not too small for your setup since I am shooting for the 240-250whp mark and want to get it as well. I know it flows better than stock and is a performance gain, that's what I said in my first post. As far as the 2.4L goes that was just my opinion (as I stated in the post). I could just imagine that adding about 80 crank hp (up to 250hp from 170hp, assuming that's what they make stock) might require a little more breathing room than the GMPP can provide.

PS-How much of a gain do you think the header and downpipe provided when complimented with your catback? In your opinion is it worth the money? I just ask because both of those components tend to be expensive no matter who you get them from.

 

NO the stock has different size piping (different sizes for different lengths of pipe) at least as far as the 2.0 went but as I understand it they are the same but overall the stock is a 2.5. the gmpp is a 2.25 thoughout the entire pipe.