I know this probably has been asked before but I can not find an answer. A bit after I bought my 05 Powerstroke I put in a MBRP 4" Cat back exhaust and now I am thinking about doing a Cat delete. I can only seem to find either CAT delete pipes for stock or for MBRP. The MBRP delete I read does not work with the stock downpipe and the stock delete pipe will not fit my 4" exhaust, so is there a delete pipe that I can get that will work with my stock downpipe and 4" MBRP exhaust? Can I get an adapter to go from 3.5" to 4"? Or do I have to get the downpipe as well?

 

just have to get an adapter

 

If your running the OEM downpipe and cat...where is your MBRP taking over? I'm going to assume it's right behind the cat. If so, you've got two choices:

(A)If you want to keep your factor down pipe you could go to a local salvage yard and pick up an exhaust pipe from a '99-'02 SD that won't have the cat. Then cut it to the length you need. Sort of like this: https://www.ford-trucks.com/forums/9...ml#post8281083

(B)Or just call MBRP and see if they'll sell you the rest of the pieces to finish a 4" turbo back system. I'd explain to them you have it from the kitty back...so I'm sure they could sell you the down pipe & kitty delete.

 

Why not just gut the cat then when the powers that be look under the truck it still looks stock at least to the point of the cat. Likewise with the egr cooler rather than remove it and risk the problems with inspection down the road, just plug it and forget it. Just my thoughts.