Although springs and pushrods aren't required with 1.9 rockers, I highly recommend them, espeically with higher limiters. Some people have no problems using stock springs, and others have horrible valve float. Our SSEi has 145k on it and has had the 1.9'* on it since 70k. It has otherwise completely stock valvetrain and gets no float even at the 6200rpm limiter it has with the DHP, however that doesn't mean another car will do the same thing, this could be a freak case. The GTP got horrible float with 1.9'* before the springs and that was with OR pushrods, so it varies from car to car. We have stock springs and pushrods in the Monte and it doesn't get any float either, but it is still low miles (around 16k or so IIRC) and has stock PCM so the limiter is low.
However, if you get springs, you don't need to go any higher than 90lb. springs. More than that is overkill unlesss you plan on getting a really large cam in the future. 90lb. springs are good to .550" lift, which is sufficient for most L67 cams.
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!