Stupid question of the day, here's where I am at: I am purchased a M085171 (41" straight donaldson muffler) which is a straight 4" inlet and a 4" straight outlet for a replacement on my stock 4" muffler on stock 4" exhaust. I understood my existing muffler could be directly swapped with this muffler, but now notice that the stock muffler has an upper inlet and a low outlet, and doesn't appear that I can get the new muffler to work. Has anyone else experienced this during a muffler replacment? If so how did you modify it? with a piece of 4" drop down, to line up the new straight muffler and if so does that hurt anything to do so? Or do I have to replace the entire tailpipe which looks to be in good shape. Please advise me as this is my first attempt at this repair.

 

I had 2 45* bends welded together to make up the offset cuz I didn't want my tail pipe at a weird angle, here's a picture, more in my gallery...

 

Thank you fisherguy. Do you happen to remember the radius of the 90's they welded together? I am having a hard time finding anything less than an 8" radius locally.

 

No I don't, I think they we just listed as 45* offsets.
Another thing you can do is look for a muffler delete pipe that has the offsets close enough together that you can get it and the muffler in. Having a short box makes things a little tighter.

Some guys just put the muffler in and live with the tailpipe at an angle, up to you.