they have a SI/DO magnaflow muffler on amazon and with the said discount of 30% from this site, it will be like 70 bucks.

my question is will the dual 2.5" out be too big to run 2.5" piping all the way out the back, will i loose to much back pressure?

should i just get the muffler and have the shop use 2.25" pipe? either size pipe will not be mandrel bent so that will have some restriction

 

If you still have stock cats your backpressure should be fine. I have true dual 2.5" all the way.

 

yeah my plan is to have from the factory y pipe 2.5" in to muffler dual out 2.5" pipe. removing everything after the stock y and replace.

 

You will be fine, I would get rid of the stock y pipe. Here is a clip of my exhaust.
http://www.youtube.com/watch?v=eTmNzBD7u2I

 

The 30% Amazon code has expired, unless you found a new one.

 

Blown, thats evil, you have to tell him it wont exactly sound like that with the whistling sound

 

I'm running 2.5" flowmasters on my '08 SLT and its runs and sounds fantastic. It is the complete setup including the muffler, extension pipes (running duel rear exhaust) and cat-back.

 

LMAO, no but he can still rumble.

 

I did a cat-back earlier this year which has the 2.5 dual outs. The truck is basically stock except for a SC tuner. I could never peel out going straight from a dead stop, but I could get the tires smoking if I stood on the brake with the stock exhaust. After I put on the cat-back, I lost enough back pressure to the point where I can barely get them to spin when I stand on the brake much less smoke now. But, when I get it on the freeway it will go like a bat outta hell.