We drilled 3 1/16" holes in the 160 t-stat we put in the GTP. It takes 10 minutes tops to warm up, and once it gets warmed up it runs a toasty 165 degrees all the time, winter or summer, and at the track we use the fan switch and keep it at 155 degrees, that is where all the power is made. I would not drill more than 3 holes, as it is very unnecessary, and even 3 holes will probably set the SES light, but its disabled in the GTP so it doesn't matter. We drilled 2 in the SSEi'* 180, and it works plenty good, we only have 3 in the GTP because it isn't driven in the Winter (except for VERY rare occasions) so we don't care how long it takes to warm up. The SSEi is driven all year round, but I think 2 holes would be too much if it didn't have those nice seat heaters. Anyways, drill 2 or three holes and it should be plenty, more than that and you aren't gonna be happy.
1990 Maroon Grand Prix STE McLaren 3.1 Intercooled Turbo, 14.695 @ 94.49 on 12psi before cam/heads/etc.
1990 Bright Red Grand Prix McLaren 3.1 Intercooled Turbo, 14.819 @ 92.72, 189whp
1999 Grand Prix GT 9.75:1|K&N|160 tstat|No Ubend/Cat/Res|UD Pulleys|Ported M90/TB/Heads|XPZ|2.55"|Pacesetters|Stage 2 I/C. 12.442 @ 112.78
2000 Blue Bonneville SSEi Supercharged Gutted Airbox|K&N|3.4"|1.9'*|WP Pulley|Custom DHP|180*stat|41932'*|No Cat. 14.681 @ 94.80
2002 Dark Cherry Grand Prix GTP Supercharged & Intercooled
12.084 @ 114.38 w/1.743 60', 315.6whp, Fastest Stock Cam M90 GTP!
NOW XP CAMMED, 340.6whp with XP, stock heads, Gen 3 M90, 11.984 @ 115.84 w/1.750 60'!
Most HP Stock Heads Gen 3 M90 GTP!
2004 Red Monte SS Supercharged K&N|3.4 Pulley|1.9'*|180*stat|41919 plugs|3" dp|No cat/ubend|DHP|Shift Kit. 14.2 @ 98
GOT BOOST??? Friends dont let friends drive stock!