mine was also hitting the crossmember bolts so i wedged a piece of heater hose between the bolt and the exhaust. it hasnt melted yet. its pretty cold here so if i dont have to take it apart yet im not going to. its probably not the best way to fix it but it works

 

I did the same exact thing with the heater hose Muk. Its been there for almost a year, thru the Jersey summer,not a hint of melting.

 

I know when I installed a non-mbrp 4" system on a 6.0 it was VERY hard to get the system to NOT hit at multiple places. The thing about these 4" systems is that at times they are forced to make the pipe close to the shock while making the jump over the rear axle, and close to the cross member on some. Most systems are quite roomy coming down the long stretch...its the front crossmember and the shock/spare tire area that gets crazy tight. I have had to hammer a dent in for more clearance to stop the pipe from impacting. Thats an extreme case, but sometimes you have to work with what you got.

If I can also recomend one other thing to youe muffler bandits.....stay way away from those old fashioned junk u-bolt clamps and get you some of the stainless steel band clamps. They will not crimp/bend the pipe and if you ever need to get it apart, it is as simple as taking the band clamp off and sliding the pipe apart, and putting new band clamps on. They are a one time use clamp, they do cost about 8 bucks each, but they will make your life SOooooooo much easier if you ever want to say....put a cat-delete or muffler delete pipe on. Have you ever tried to take apart a pipe intersection thats been crimped together.....tough!