thenrie

Hey folks,

I'm going to need to repair/replace my exhaust system soon. I've done a bit of forum research and the best thread I found was from 2007. Just wondering if anything has changed.

My 2005 3500 DRW, 5.9 truck now has 322K miles on it, but I lost the engine a while back, due to a bad injector, had it rebuilt. Howsoever, my turbo was still fine, so it went back on the rebuilt engine. I often haul a pretty heavy horse trailer and occasionally a very heavy 40' trailer when hauling hay. I'm in a mountainous area ranging from 4500' to well above 7000'. I have seen my egts get pretty high. I've been looking for ways to keep my egts in check, while pulling at a reasonable speed on climbs.

I currently run a stock engine with a few add-ons, such as an AEM cold-air intake and a 4" exhaust system with a cat, but no muffler and a Bully Dog Triple Dog Power Pup tuner. I also have a BD exhaust brake on it. I think the old engine had 50hp injectors, but I now have stock injectors on it. I may go back to the 50hp injectors eventually.

So, the question is this: With a turbo that has over 322K miles on it, maybe an upgrade in that area might be a good idea. It would not be a radical upgrade, because I want to be able to keep the BD exhaust brake. So, with that thought in mind, should I stay with a 4" exhaust system or go with a 5" system? If I go with the 5", I would have to delete the cat converter. Should I go straight pipe, turbo-back or with something like a Donaldson 51" muffler? I realize a 4" exhaust system is fine for my stock engine, but if I replace the turbo with one more suited to my towing habits (and just because I'd love a bit more power) would a 5" exhaust system be a better choice? I've read that below about 700hp a 4" exhaust system would give me better low-end performance than a 5" system, but I've also read that the 5" will lower egts. I don't see me reaching 700hp, but I might reach 550 eventually, with the turbo upgrade and 50 or 100hp injectors.

So, replace the 4" cat-back no muffler system (maybe add a muffler to kill the drone) or a 5" turbo-back system with no cat and a straight pass through muffler, like the Donaldson? Keeping in mind, of course, that I may upgrade my turbo in the not-too-distant future. I'm not too concerned with sound. Good sound is nice, but I'm more concerned with performance.