will a flowmaster stock style muffler fit without any modification to my stock exhaust setup? Will there be a noticable difference in HP after installation?

 

most likley yes, but u will need a way to have the exhaust exit after the muffler as you might not be able to reuse ur stock tips, and make sure the muffler u get has the same inlet sizes as what u have now. flowmaster will give u a little gain over stock