Bigluke

Okay so I installed my new muffler went with a flowmaster 40 series just single in single out and had the resonator removed it sounds good but there a weird noise almost like a exhaust leak but check all the welds there good. Could this be the stupid valve behind the muffler and should I remove it

Did you notice any power lose when dumping it

Would magnaflow be better or just dnt dump it

So I have a 2014 silverado and wanting to put a flowmaster 40 dumped if I cut the muffler off including the valve and resonator off it won't mess up my truck or make any check engine lights come on will it