leaky y pipe from lpp
so i finally got around to putting on my new lpp longtubes and there awesome dont get me wrong but i just cant get the y pipe to seal up.i used band clamps like everyone on here said to do and put some copper permatex where the pipes overlapped but i can still hear the exhaust leak and when i crawl underneath i can physically feel air coming from the y pipe i checked and all the clamps are as tight as they can be. so here's my idea i wanna run by yall. ive got a pipe expander so i was thinking about enlarging the pipe so the fit would be nice and snug but part of me says that the band clamps just arent doin it. i really dont want to pay 50 bucks a clamp for those really good ones but the u clamps crimp the metal so if any one has any input on what to do please let me know. also is it common for the y pipe to rub on the front driveshaft?
1999 chevy silverado Z-71- 5.3, CAI intake, catback, nelson tuned, lpp lt's, vette servo, e-fans.