I have the GMR 98 inch kit with 9:8:1 compression.I put the S-E 32996-01 plugs in stock to slightly modified engines .The 32997-01 say it is a slightly colder heat range for high performance engines with raised commpression.Will that adversly effect performance?Or there is no real noticable difference. thx

 

MaxEvo,You can use whatever a stock Evo used.My 124" EVO motor has had them four years and not one problem.Dog