GTP'* brakes are 1" smaller. I am almost positive 15'* won't fit on an SSEi. I know that GTP'* have a problem with some of the stock wheels fitting with aftermarket brake kits that have bigger rotors (which are the same size as the stock SSEi rotors), so I really can't see 15'* even coming close to fitting. Is there 2" clearance between the calipers and your stock wheels...I'm pretty sure there'* not.
Slicks will sure drop your track times. I'm personally looking for a set of slicks for my STE...when I get up the courage to bring it to the track with tranny number 3, I'm not gonna mess around. I'm also going to run 100 octane gas and also try to run 12psi. I run 8.5 on the street, and usually ~10psi at the track (still on pump gas, just don't like to stress the tranny as much on the street), but when i get to the track I'm gonna make it count. I'm gonna try to get deep into the 13'* with the stock turbo, in which people have said isn't capable of putting one of these cars into the 13'*. By my calculations, it *should* easily do ~13.5'* with a 1.8 60'.
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!