That is a huge friggen pulley!!!! An M62 with that size pulley is not going to move much air. Even on a 2.5L.
Do you know what your volumetric efficiency is on that engine? 2 valve per cylinder or 4?
Assuming 100% volumetric efficiency your engine flows 265cfm.
Your pulley ratio is 1.47. So your blower is spinning 1.47 times what the engine is. So at 6krpms your blower is spinning ~8842rpm. Assuming your blower is 100% efficient it pushes 312cfm at 6krpms based on my calculations...which are prolly wrong cause I suck at math. But anyways, looks like you need a much smaller pulley to me. 312cfm = not a whole lot more than 265....
With a 3.5" pulley so your pulley ratio is 2.0 and your blower will be spinning 12k at 6krpms. Thats 423 cfm air at 6krpm. Which looks like ~8.7psi.
These are just rough estimates and I could've easily screwed something up along the way so take these with a grain of salt.
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!