Now that I've found out that Cobra underdrive pulleys work on my Mark as long as I use the 96-01 Cobra belt, my question is...do they make a difference on a Mark? Do they actually free up any power?
Any takers on this one?

I replaced the crank and water pump pulley with a set of Steeda pulleys. I didn't need a new belt. That gave me about 5 rwhp gain throughout the entire band on a dyno. It worked out to $20 per hp.

I replaced the crank and water pump pulley with a set of Steeda pulleys. I didn't need a new belt. That gave me about 5 rwhp gain throughout the entire band on a dyno. It worked out to $20 per hp.


you woldent think that would make a diffrance but yha never know, what was the weight diffrance between stock and the stedas?

you woldent think that would make a diffrance but yha never know, what was the weight diffrance between stock and the stedas?I'm not sure if there was any at all. Both of the crank pulleys have balancers on them as well, so they were both relatively heavy. The main difference is the diameter of the pulley. Smaller crank pulley means less drag to the accessories which increases hp to the drivetrain.