I did a search and it didn't come up with much but heres the issue. When I shift into 3rd or 4th after doing 6000 RPM or more in the previous gear there is a grinding noise, it isn't that bad and the selector goes in without me forcing it in but how would I fix this? The rest of my gears are fine.

my car is a 1992 Acura Integra GS with B16A in it.

 

This is actually pretty common for Da's,especially ones with high mileage.You can drain your manual tranny fluid out and put Synchromesh fluid from any GM dealer,or buy the Penzoil Synchromesh like I did and replace it with that,works great,at least for me it did.Mine wouldnt go into reverse on the first try,especially if it was cold and I had the 3rd to 4th high rpm grind as well,both now gone.Dont expect a miracle though,if your tranny needs internal repairs,like a bad synchro,you should have that looked at by a qualified shop.

 

yeah i got a 210k and mine grinds from 2nd to 3rd. Its no big deal if you take it easy. Its just your synchros. Mine have done that since 195k. I also have heard great stuff bout Synchromesh a buddy used it on his tegg and its been perfect ever since.