So my Evo 4 has always been very noisy drivetrain wise. As we all know 4G63's are loud motors especially with an intake and a straight pipe haha. Anyway I get this whining sound at about 2500-3500 rpm (so cruising rpm). I was convinced it was my tcase making the death whine, and as I have an extra trans/tcase I was more than happy if I had to switch it out. So I drained my tcase oil and it came out perfectly clean (14,000 km since I last changed it). No silver or anything. I properly refilled it etc and decided this was a little over my head. I took my car to a local JDM shop/tuner that I have had great experience with. They said they narrowed down the possible noises I'm hearing to simply just a noisy driveshaft and the combination of a lightweight flywheel and my comp stage 2 clutch also makes a fair amount of noise in lower RPM. The sound isn't nearly as extreme as any of those tcase whining YouTube videos and there is no tinging sound or anything of that sort. Opinions? I know sounds can be pretty much impossible to diagnose through text, so I may make a YT video later.