Hey, I was over my friends house. Hes got a 97 powerstroke with an intake system, chip, injectors, and exhuast 4 inch down pipe. I got my dads 02 7.3 and we bought it with a Airaid intake system, BUT! Its got the stock exhaust. He said without the muffler off or somthing done with the down pipe, preferably a kit, the intake system aint doing anything for it. Is this true??? The guy knows alot about diesels and hes selling his truck and im thinking about buying it.

 

Your friend is right. You got a large intake going in while your exhaust is smaller. This creates a back pressure. What you want is as free flowing as possible. IMHO just doing a down pipe and or muffler won't do any improvment either. Your whole exhaust must be the same size to allow the same amount of air flow.

My plan is to get a 4" - 4.5" down pipe off the turbo and then split to dual exhaust of about 5" .... I'm checking into the laws in my state, but I've heard that the turbo is considerd a muffling device.. so a lot of people are going without mufflers and cats. Which I will do if I can get away with it at inspection time.

 

BUY IT and then put a 4" or 4.5" turbo back exhaust kit and either split the exhaust to a dual 5" tip or single 5" tip. It is up to you if you want to go with a CAT or no CAT. I dont have one and it sounds MEAN. IMO go without the CAT.