Ive read all of the info on putting a smaller pulley on the stage 2 and it seems to me that the 2.9 is the safest way to go. But is a 2.9 pulley really making that much more hp than the 3 inch. If so how much hp.

 

there are a lot of posts on this that you could probably find, but i'd say maybe 8-15 hp difference depending on supporting mods. I dunno if anyone has done before and after dynos, but i can say that from stage 2 (3.06" pulley) to 2.9" pulley i don't have anymore traction at any rpm if i go WOT in first on nice dry pavement with my stock tires.

 

the biggest difference i noticed was in throttle response. when you get both of the pulleys in your hand, you will truly notice the difference in weight. and you cant forget about that awesome whine it makes

 

By going from stock to stage 2 you shave .29" off your S/C pulley size. by going from S2 (3.06" pulley) to 2.9 you are shaving off an additional .16" off the pulley size. Not to mention the difference between the weight of the pulleys. Consider the 2-3psi gain you get from S2 and you can see that an additional .16" (roughly 50% of stage 2 gains) will probably net you 1-2 more psi and obviously a few more ponies.

hawlyns711 went from 205whp 191wtq (stock) to 244whp 228wtq by adding I/E/S2 Tune/GMPP Extrude Honed Manifold/and his 2.9" pulley (+34whp 37wtq)

chevysalesman614 dyno'd 245whp 214wtq with the same mods as me currently, AEM Intake, Magnaflow Cat-back, 42.5lb/ft injectors and I got 228whp, 204wtq. He however may have had a tune at the time.

These results can be found here: https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/please-post-your-2-9-dyno-s-83126/

Even so, we're not talking small insignificant gains, these are nice gains especially for the money. I would estimate 4-15hp depending on supporting mods/tune.