I searched and read tons of threads on the donaldson MO85171 40" and the 50" I just ordered. Well coming from running a aero turbine 4040 for two years now I think Im ready for something quieter ........... My truck came with no cat...so my question is, coming from the inlet side of the muffler is my exhaust 3.5 or 4 " ? I know the aft section of the exhaust pipe is 4"Od. Will the muffler slip right on or do I need to but some adapters from airflow ? Im going to try and knock it out on a weekend and want to have eveything on hand seeing how I live in the "country" and parts arent readily available. 2003.5 w/ no cat........ well let me rephrase this......I have all the tools ect to do the job, just need info on direct fit with reducers ect...Thx in advance.

 

Your exhaust is 3.5" from the turbo to the muffler. 4" thereafter so you will need an adapter for the new muffler.

 

thanks for the response. Guess I'll be ordering a 3.5 od to 4"id and 4"od to 4"id adapters. I'll mic it out first and get some measurements. Thanks

 

Your stock muffler is 3.5 inlet/outlet. The tail pipe goes from 3.5 to 4" right after coming out of the muffler. you need two 3.5-4.0 adapters.

 

I'm curious if changing out to this muffler will lower egt's at all. Do you have a gauge and if so can you note any changes pre and post muffler swap?

I noted on mine that running spot on 70mph on flat ground, 6th gear I'm right about 700*

 

You will also need a small can of elbow grease.
Some members here substitute it with a large case of beer.

 

no, sorry I dont have a gauge to read temps. got the muffler in monday, shes pretty huge to day the least. Ordered my adapters from air-flow yesterday....