I have a baisically stock 01 2500 cummins. I just ordered a Smarty and have an air intake on it. I want to put an exhaust on soon but not sure if i want to go with 4 or 5 inch. I plan on gettin bigger injectors, turbo, and would likt to get my tuck up to around 600 hp. But will the 5 inch hurt me till i get up to a certain hp level?? im also lookin for the best sound.

 

If your going to change it might as well go big. I know my 4" turbo back makes 532 and it's through the muffler too

 

5" will not hurt your performance. It will give you a slight deeper tone compared to the 4"

 

Thanks guys 5" it is!

 

might be late, but the 5" might be a snug to get a 5" down pipe off the turbo. When I had a stock turbo, the 5" wouldnt fit right without rubbing on the firewall. You might need to go with a 4" down pipe then bump up to the 5"

 

The 5" Kits still have a 4" Down Pipe

 

5" is the way to go!

 

i have a 4" down pipe to 5" and i love it. not sure what my hp numbers are but it sounds GREAT.

 

Any clearance problems with the tranny??

 

Not that I have ran into.