[bird01]

what is the general consensus on under drive pulleys? i've been hearing different things about how beneficial they are overall. im thinking im going to start with a cold air intake. any brand suggestions?

[Bullitt95]

Underdrive pulleys produce bigger HP gains on more highly-tuned, higher-revving engines but you can still install them on a relatively stock engine.
I suggest you only do the underdrive crank pulley so you can avoid the charging problems associated with the u/d alternator pulley and the idle overheat problems of the water pump pulley. If you plan to bypass the smog pump +/- the AC, that's probably the time to install the new pulley so that you'll only need to change the drivebelt once.

[RLG34750]

Originally Posted by Bullitt95

Underdrive pulleys produce bigger HP gains on more highly-tuned, higher-revving engines but you can still install them on a relatively stock engine.
I suggest you only do the underdrive crank pulley so you can avoid the charging problems associated with the u/d alternator pulley and the idle overheat problems of the water pump pulley. If you plan to bypass the smog pump +/- the AC, that's probably the time to install the new pulley so that you'll only need to change the drivebelt once.

+1^^^^^^

but there are some cars that are not affected with those problems...

especially those with electric fans.....

[Bullitt95]

Depends. On an engine that'll rev to 6500+rpm, an underdrive water pump pulley might be beneficial. By slowing down the water pump at those high revs, the risk of cavitation and loss of coolant flow is reduced. The other alternative is to install an electric water pump so that you have a constant rate of coolant flow regardless of rpm and plenty of flow at idle.
Using an underdrive alternator pulley in the same situation will prolong pulley bearing life by reducing its rotational speed.

[Big Daddy's Stang>]

Originally Posted by bird01

what is the general consensus on under drive pulleys? i've been hearing different things about how beneficial they are overall. im thinking im going to start with a cold air intake. any brand suggestions?

On the cai q. k&n, mac, bbk, steeda, jlb are some of the popular ones...

[Bullitt95]

I have the ASP crank pulley.