After going back and forth between si/do and si/so I've decided to stick with the si/so setup. I'm wanting to go with a 3" pipe for that little extra performance and low end torque but can't find a muffler with a 2.5" in/3" out. I'll probably go with a 3.5"x18" 15degree rolled tip to finish out the look. Oh, I'm wanting the 18" magnaflow for the not 'too' loud sound. Am I missing something with not being able to find a 2.5" in 3" out muffler.

thanks,,,

 

Bigger pipe = less back-pressure = less low end torque.

 

You'll want to begin the 3" pipe at the Y, that way you don't have the restriction at the intermediate/mid pipe. the 18" Magnaflow you might want is #12249 (3" SI/SO center/center)

you can even get a new Y-pipe Magnaflow # 10778 for better transition.

I went with the 24" body because I removed the rear cats first, and it was loud as hell. But I'm glad I went 3" y-pipe-back


EDIT: the whole bigger pipe = less torque debate is something I don't agree with to a certain extent. People run true duals with no problems, so why can't you run the same volume/pressure through a 1/2" bigger pipe? I know there are math formulas to figure out the whole 4 cyl.thru 2.5" pipe x2 vs. 8cyl thru 3" pipe, but it's too early, and it's Saturday, so I'm not doing math...

 

I think the whole 3" pipe is debatable, but according to this write up it'll improve the trucks hp by 14.7 at the wheels.

http://www.troyerperformance.com/cgi...atalogno=15821

 

Order a Magnaflow Y pipe piece thats 2.5" dual in to 3" single out, and un it all 3" from there. 3" single exhausts are much healthier for these trucks. The original Y is restrictive ( dual 2.5 going to 2.5 single.. )

Heres the Magnaflow Y http://store.summitracing.com/partde...5&autoview=sku

Heres the 18" body with the inlet.outlet configurations I would go with http://store.summitracing.com/partde...5&autoview=sku


And heres your option list of 3.5"x18 Magnaflow tips. http://store.summitracing.com/egnsea...115+4294783516

 

If you just purchase that kit then you'll be good to go. The pipe before the muffler is reduced to the correct size. If you're not going that route then you can always have a shop reduce a pipe for you.

 

The muffler Darren posted is 2.5 inlet and outlet, you want part number 12259 for the 3" version

 

Thanks guys!!!!

 

shoot, good catch man. I keep dealing with these guys that want stock muffler replacement only lately

Here is the correct muffler. http://store.summitracing.com/partde...5&autoview=sku

 

also-a chain is only strong as it's weakest link-it's still 2.5" from y going into muffler

 

Hey guys, was just under the truck looking at the Y pipe and the shape doesn't look like the Magnaflow Y that was posted above. Will the Magnaflow one still work?