need help, standard trans grinding in my vert

[big_tuna]

I've got a 93 convertible. I bought it already 5 speed swapped last year. The trans. grinded bad in every gear up or down shifting. I checked the oil it was good so I decided this spring to pull the trans and swap in a different one.

I changed the trans, clutch/pressure plate, put in an oem nissan throwout bearing, slave cylinder, and master cylinder. The clutch is just an Exedy replacement, and there was an almost brand new light weight flywheel in there already.

I noticed after a couple weeks of driving the trans started grinding just like the old one. If you put the clutch in to down shift there is a terrible grind even before pulling it out of gear. It wont grind at all if you rev it before downshifting at any rpm. If you up shift at 1500rpm it shifts fine. Any higher it will crunch in every gear.

I wanted to autocross the car this year but any kind of quick shifting into second is impossible, it wont go in! The oil is new 80-90, the pedal is properly adjusted, the master cylinder has clean fluid.

I'm just baffled that 2 different transmissions would have the same symptoms. Is it possible the replacement pressure plate may not work well with a lightweight flywheel?

Sorry for the long post! I'd really appreciate some advice because i'm stumped!