02BlackMachine

after i put my car in drive today , i was hearing a weird noise ...grinding in a way .... i only heard it when in drive , i tried neutral and park and i couldnt hear it ....i recently installed my cutout's for my y pipe and i had them closed, when open i cant hear it but when closed i hear it going to about 25 mph and then it goes away. could it be something internally ???? i did race a mitsubishi lancer evo yesterday with my cutouts open (smoked him and my car backfired as i was flooring it .