1999 gsr:

at high rpm, 3rd gear grinds when upshifting. heel-toe downshifting is fine, but not smooth. rev matching helps the upshift a little, but not much. will a synchro sleeve set from a 1999-2000 civic si fit my car? parts number is 23623-P21-315. at this site.
https://www.hondapartsdeals.co...M++14

 

me also had the same problem. some of my search found the same parts number with you. but some of the search i found is : P/N 23623-P4C-308, H/C 6780811
which one is correct one?