Hello, so I been having my 2010 G37 coupe for a while now and I decided to buy test pipes, not the smartest first mod I know now but now I notice a rasp. So I went ahead and bought a manzo axel back hoping to take away the rasp but that didn’t work ha. Did make the exhaust note sound way better though because before the G had muffler delete from the previous owner so it was loud af. So back to the raspy ratreling noise that I hear from 2-3k rpm upon acceleration. Could it be the stock y-pipe heatshield making the rattling noise? Or could it be the z1 test pipes which are 2.5 in diameter. What would be the best thing to do? Should I just drop 600-1k on a catback ? I do plan on getting a tune after either buying a catback or if there is a cheaper route by buying a y pipe and keeping the stock mid?