Underdrive pulleys

I'm thinking of putting them on at the same time as when I put on my 5% blower pulley. i've asked a few people and they're split about them. I will not have a big system so I don't need huge power comming out of my alternator. However I do worry about cooling since as we all know SC's run pretty warm.
Has anybody used them? Benifits vs problems?
Thanks in advance!

theyre great i have used for 6k without a problem im even running the more agressive march underdrive WP pulley without problems.

but if i had to do it again ill chose the SCI kit weights even less and the alternator keeps full charge.

less weigths = more power.

Personally, I would spend that money elsewhere. I had them on my car and gained like 3 RWHP on the dyno.

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I thought SCI is still developing their UD pulleys? Are they ready now? Maybe the lighter weight and change in size would add more than 3rwhp

the sci is stock sized , but by keeping the same size (smaller than ud) and by reducing the weigth , you get a more than 3rwhp maybe 8-10 but the trick here is that they put a lot less stress in the engine , and allow you to rev a lil bit faster.

as comparison , sometime i run my engine without the supercharger belt , and before the aluminium pulleys it felt extremely anemic , after them it feels much much better , the engine feels a lot ligther.

There fine, for a minimal pwr gain. I have run them for about 3 years on my CMRE stage 2, but now while considering the MP,FMIC I think it will be wise to get a set of the SCI pullies in trade for blocking the Radiator.
If your trying to squeeze every bit of power out of a stock SC with bolt ons then there worth it & you shouldn't have any problems associated with them.
But there not nessesary on highly moded motors (not recomended)

I really don't want to have to rip my engine apart so I'm mostly going to stick with bolt ons. Exhaust, MAC intake are done. OD/UD pulleys, cats, 8.5mm plug wires, lightweight jackshaft pulley and maybe a bigger MAF are next.
Thanks guys.

The MAF won't do you much good unless you change injector size, & if your gonna go with a 10% OD pulley, then I'd consider that anyway. Pulling the SC and changing injectors isn't that tough.....with the Mods you've done & the ones your planning a set of inj would be a good choice (38lb on 89-93 & 42s on a 94-95) & you will see some improvemnt in performance, Then spent the money on porting the SC. Get a 73mm C&L MAF with the sample tube for the appropriate inj. This will really wake your car up.
Your car will run fine with those step-ups even without a tuner or chip. They are well within the stock EEC tables range.