which should i get first?

[gftb5]

an underdrive pulley or CAI

[wildstringer]

i know im going to kick myself when ya tell me but what is CAI

[351wStang]

CAI is cold air induction. It replaces the stock air cleaner box with a conical filter.

I would suggest the under drives first. You will see very little to no gains with the CAI and surely will not feel the gains. If you wanted to see the gains you would have to dyno the car before and after. Personally I think CAI is just a rip off.

[brentmcq]

I would go with the CAI first. The underdrives are good if you plan on getting lower gears to slow down the accessories up front. UDP's only give another 5hp and CAI can give 10-20 depending on the vehicle. I have both on my 2000 and noticed a bigger jump from the CAI.

[wildstringer]

well they both will add about the same hp at least thats what they are advertised i just think the cold air is more for looks though .by the way i knew id kick myself.

[351wStang]

Originally Posted by brentmcq

I would go with the CAI first. The underdrives are good if you plan on getting lower gears to slow down the accessories up front. UDP's only give another 5hp and CAI can give 10-20 depending on the vehicle. I have both on my 2000 and noticed a bigger jump from the CAI.

How the hell does lower gears slow accessories?

[wildstringer]

well it ... yeah theres the...wait a minute yeah what 351Stang said

[SVTcobra306]

I think what he's getting at is that if you put lower gears in the rear with stock pulleys, your accessories turn faster due to increased engine RPM at a given speed, with underdrives they'll slow back down.

My .02 cents: CAI gives you the same gain as a K&N replacement filter, just looks better. UDP's are nice but can cause some quirks. Look to your exhaust for gains.

[GTStang]

I'd go UDP over CAI neither one gives you real large gains but I think the UDP actually give you someting where I feel CAI is mostly looks. Plus UDP for 5.0 and 4.6 don't cause any issues that happened in there earlier days so no drawbacks to them.

[SVTcobra306]

Oops, yeah, I always forget that my UDP's are ancient March ones....They do cause me some charging issues...

[brentmcq]

It's a toss up. BTW my earlier post was in favor of UDP's "if" lower gears are put in the rear. The higher rpm's increase wear on the accesories, the UDP's will help them last longer. CAI is easy to install, UDP's require pulling the balancer off which is no big deal it just takes longer. Most stock air boxes are very restricted. More air in and more air out = increased HP. Pesonally I'd go in this order: cat back, x-pipe, cai, throttle body, gears, UDP's.

[Ace$nyper]

well being the mustangs intake is pretty good i'll say pullies would be better

[Red 99 Mustang]

how much are udp's? and what do they do?

[StillGoin5.0]

cold air induction

[andrewespo]

Originally Posted by Red 99 Mustang

how much are udp's? and what do they do?

Underdrive Pulleys range between $80 and a $130. Depending on application and metal chosen (steel, aluminum). Underdrive pulley kits basically free up excess power from crankshaft, water pump, and alternator pulleys giving you a little horsepower.