Just a quick test I recently did with big a Sun tach hooked to my 140 PG. 205 60 13 = 3200 at 60 195 80 14 = 2800 at 60 185 70 13 = 3000 at 60 The RPM could be +- 10, but relationship is there. The WOT acceleration at 3200 with the 205 is quite impressive. Still running 87 octane. MIKE KOVACS