Hey all, I'm having a weird high pitch exhaust rattle at certain rpms (approximately from 2700-3200 and 3900-4200). I have a 95 civic Si (Canadian model, which is same thing as the ex in the U.S). I swapped a b18 (gsr) engine in 2 months ago and had no issues with the stock exhaust. I recently put on full 2.5 inche custom exhaust with a vibrant performance muffler (not a fart can, looks more like a stock muffler but with a slightly bigger tip) with no cat or resonator. I noticed this rattle the second i drove it after getting the exhaust done. So I replaced the muffler with a new, but same style muffler. Still the rattle. Removed all heat shields around the exhaust. Still the noise. I also check all hangers and wiggled my exhaust and didn't hear the noise. It only happens while at those certain rpms. Help or suggestions would be greatly appreciated! Thanks in advance.