What are the pros and con of either exhuast system I put on mt truck. I have a 02 chevy dmax 6.6 and hear conflicting stories about I need the cat for the back pressure and its better to run from the turbo back for the horse power. Can anyone shed some light.
There is no Pros for going with a Cat back system. The only reason why you would want to consider a cat back system is if you have emmissions testing in your area and know you will be checked periodically to make sure all smog equipment is in place. Who ever told you that you needed to leave the Cat for back pressure needs to go learn that gas engines and diesel engines are completely different in most ways, exhaust being a big one. A turbo diesel does not want any back pressure at all. The turbo creates plenty.
In your 02 Dmax you don't have a cat. Only the 04.5 and up have a cat. If your going to get exhaust get a turbo back system. waytogo You are correct that the 04.5 and up trucks can have issues with not having the cat and muffler creating back pressure to keep the egr system happy. There are several different ways that you can cure this issue though.
Agreed, turbo back. The stock "down pipe" has a serious restriction in it. But make sure you get one that really does offer turbo back and a non-kinked down pipe. Some of the adds are misleading and they don't actually replace the down pipe where the worst kink/restriction exists. Than again, you can get something like 80%+ of the benefit of a full 4" exhaust by only replacing the muffler. From all accounts, the stock exhaust flows quite well enough for moderate power outputs when you only upgrade to a free flowing muffler. Most of the ballance of that missing 20% is supposedly in the down pipe, and the rest of the 4" pipe has almost no measurable effect (IIRC). Whether you need the extra bit of flow (primarily visible only in EGTs) or not is up to you...
If he's in California, he has a cat on an '02. I removed the cat on my '04 with a 4 inch turbo-back system. More turbo whine, about 100 degrees lower EGT, and better spool up. The only one that I hear has problems with removing the cat is the LLY motors, which can throw an EGR code and funk with the computer. Marc
If your worried about messing with the emissions components of the truck, just have an Aeroturbine installed. I noticed a 100-150* drop in EGT over the 4" exhaust w/standard muffler. I can imagine deleting the stock muffler and installing an Aeroturbine in it's place would give a decent drop in EGT and a mild boost in performance.
