I hope this isn't a noob question...

I'm not the world's fastest shifter, but I can get the timing down good enough to chirp the tires w/ TCS on from 1st to 2nd, occasionally 2nd to 3rd. But here's the problem...

When I make that same 1st to 2nd shift with TCS off, it feels like the transmission is grinding. Naturallly, I thought maybe in my attempt to shift quick, I let the clutch out too early. So I tried it again, and just left the clutch in and it still felt like it was grinding. Can anyone explain any possible reason that this only happens when the TCS is off?