Exhaust through crossmember

[MZ_69_chevy]

Has anyone here ever cut holes and ran exhaust through the rear crossmember on 67-72's? I have heard of this but never seen it. My truck is a 69 and pretty much slammed. I don't want the exhaust to sit below the frame rails much so i'm not sure what to do. I have a set of 4" pipes with flowmasters that I got from a friend out of his 69. Only problem is, his is tubbed and that crossmember is gone in his truck. On his the pipes went about 12" past the cab. I'm just curious if it is possible to get this 4" exhaust thru the crossmember without sacrificing the strength of it. Or even go with a whole new 3" setup. I really want to use the 4" though...it sounds completely badass!! Thanks in advance for any advice!