I was just speaking with John Holmes - AKA MR Diesel 101, (from Carson Dodge, Carson City NV) today about this very subject. John stopped by this morning for a visit, then on his way back home to Nevada from a visit to Texas. We were discussing EGT's. John told me that DC doesn't care about the muffler but they DO care about the CAT. If you leave the CAT and go straight pipe CAT-back it will NOT void your exhaust warranty. The true issue is about the emissions stuff ie:the CAT remaining in tact. He did say that it might be a good idea to leave the resonator, but it could go too.

So, now I'm looking for a nice, good quality, stainless steel CAT-back straight pipe system. John explained to me that getting rid of the muffler has been noted to decrease the EGT's by 100*f in the 2006 models. Sounds like that is an excellent way to reduce EGT's, maybe even gain a little mpg?

CD

 

Resonator? Oh yeah, that's the part my local emissions inspector and I call "the muffler".

 

Magnuson-Moss Warranty - Federal Trade Commission Improvement Act of 1975

No warrantor may condition the continued validity of a warranty on the use of only authorized repair service and/or authorized replacement parts for non-warranty service and maintenance. For example, provisions such as, "This warranty is void if service is performed by anyone other than an authorized 'ABC' dealer and all replacement parts must be genuine 'ABC' parts," and the like, are prohibited where the service or parts are not covered by the warranty. These provisions violate the Act.

Under the Magnuson-Moss Act, a dealer must prove, not just vocalize, that aftermarket equipment caused the need for repairs before it can deny warranty coverage. In otherwords it is illegal for a dealership to void your entire warranty because of an aftermarket product they can void the specific item warranty but thats it.

 

A rail pressure gauge can void the warranty. The others should be ok but that probably depends on the dealer and some would of them might even overlook a rail pressure guage.

 

My '03 was straight piped right up to when I traded it in 2 weeks ago..........never a question about the muffler from any dealers....

 

Ive got a good dealer (redlands dodge) they look the other way on my engine driven on board air setup, gauges, and straight pipe. They have fixed many a thing under warranty. Lift pump got updated with in tank pump, fixed an interior light, and a wiper problem. My 36k mile warranty is up, but I still have the 7 year 70k mile warranty to worry about, as well as the 100k cummins warranty.
Scott