In contemplating a Cummins swap into my 85 Chevy K30 I learn that the exhaust pipe has very tight clearances between the transfer case and the frame. It appears that 3-1/2" is as big of a pipe until you get past the T/C. Any issues with this with a mildly mod. 12v?

 

I dont see an issue with 3 1/2" Should flow fine