Well i can get a shop to make me a cat-back exhaust for 100 bux...wat size should i go with,if i plan on putting a gm s2 in the summer and also would there be a hp increase if i dont change the headers and downpipe?

 

I would go 2.5".

 

Don't go any larger than 2.5" diameter.

Also, ask them:

"What type of piping are you using?"
"What kind of bends are you using?"
"Can I add a resonator?"

The piping type might effect the actual lifetime of the piping and how easy it will rust over time. This might be important to you, especially, for a daily driver car.

The bends are ESPECIALLY important. The type of bends you get can effect your exhaust flow tremendously. I'm not going to get too in depth on the bends part but make sure they DO NOT crush bend your exhaust system. More than likely they are going to either attampt to crush bend or give you compression bends...that price is too cheap generally for them to do mendral type bends.

If you don't know much about bends, I can explain in detail about them.

Resonator will help lower the tone of the car...lower meaning deepen the town and take away the raspiness.

Will it help performance w/o a header and b-pipe change? Yes, it can but not as much. You're no matter what, getting rid of backpressure, which is a good thing. If you're capable of increasing the exhaust size of the exhaust manifold (header) and the b-pipe (or what you call a "downpipe"), there will be more of a steady flow and of course less backpressure in the exhaust system.

If you have any further questions, feel free to ask.

 

the way to do that with a shop is to buy your own mendrel bent piping and do an axel back with a muffler that you provide. i was going to do it at a local place for about $100, but the guy there was an old school mechanic that does more work on v8 muscle cars and asked me why i would want to ruin my car yadda yadda. after the experience with him i just said screw it, they arent getting my business and did it right with a Corsa catback.

 

Doesnt the SS has stock 2.5 diameter pipping?? just curious

 

I thought parts of it was 2.5" and other parts slightly smaller.

 

well Im curious bc Im looking for a stock ss catback for my LT bc I had herd it was 2.5"...

 

if im not mistaken, the piping drops to 2.25" after the axel.

it's been a while since i was looking into getting a new exhaust tho and i dont recall whether or not that is the case. just go look under your car and you can see where the piping funnels down to a smaller size.

 

Yes at the rear before it goes over the axle it reduces down to 2.25. If you would like to save some money have that part replaced as well as a muffler of your choice and it will be just as good as any other 2.5" cat back you can buy for .25 the price. The only difference is that it won't be polished like some, but who looks there anyway.

 

Thanks RBC

 

SS has stock 2.5, but there are a few places with constrictions which make it closer 2" or less in some places. These are really the only places you need to replace to go full 2.5 back.

 

The "down pipe" I believe is the only other restriction.

 

soo you guys are saying deff not get the 3inch pipe if u have the gym stage 2 with the 2.8 pulley
becasue i was thinkin about ethier takin the cat off my car and just haveing the flow master or just gonig with 3inch and a flowmaster

 

As has been stated many times in exhaust threads, 3" is too big unless you are making 350whp or better. With that large of a pipe you are greatly reducing the low end torque while creating minimal gains in high rpm HP. This is caused by the reduction in exhaust velocity. Pump 1 gallon of water through a water hose and test the velocity then perform the same test with a sewer pipe. Reduction of backpressure is a good thing to a point, after that point you start moving your power high in the rpm range and lose the off idle torque.

 

Well I just got my quote with mandrel bends and Magnaflow muffler 12256 and it was $110. Much cheaper and just as good as after market cat-back system. I think I will get in on the pacesetter header(painted) group buy and have a great full exhaust for under $300. Not to bad!

 

You doing a no resonator design? I tried just building out 2.5" from the factory resonator and putting a magnaflow muffler on it, it sounds like total and complete ass lol. I did a post in the 2.0L performance area describing my next trial home made set-up.

 

I am going to keep the stock cat and stock resonator. The only parts that I am going to replace is the Header, "down pipe", the 2' of 2.25 piping, and the muffler. The sound should not be to far from stock.

 

I found a guy that will sell Magnaflow muffler part #12256 for $61.58 shipped. If anyone is interested let me know and I will post the info.

 

where can i get a magnaflow muffler for $61? thats a good deal