Underdrive Pulleys cons and pros
 

I am thinking about installing Underdrive Pulleys in my 03 GT. Any thoughts? Stupid or good mod. I have intake and xpipe and catback already. I know they pulley's don't add power, but free up power.

Yes,they are a worthwhile modification.They will ,if nothing else,increase the life of the engine accessories,water pump,alternator,and A/C pump,by turning them slower.My last car, a Lincoln MK VIII with 167,000 mi.,had the original water pump and would have had the original alternator but for an electrical failure.Sometimes when you have a killer stereo you can have charging difficulties at idle RPM's.When purchasing,ONLY get the stand alone pulleys,not the piggyback type.The stand alone type has the harmonic balancer built onto the crank pulley.The piggyback 's do not.I have the Steeda pulleys but March also makes the stand alone pulleys.March was backordered when I bought mine.When installing be sure to remove the washer between the crankshaft bolt and the stock balancer or you will not be able to get them off and you will be in here asking why :( Also,BE SURE to use silicone sealer (RTV) in the keyway when you install the crank pulley or it will leak oil and lots of it.You might have trouble with the alt.pulley ,if so remove it and take it to Advance or Autozone and let them take it off for you.Happy Motoring.

Pulleys are good...Everything Chopper said is perfect...I would say go with Steeda...

team them up with a steeda timing adjuster :cool:

-Mike

Well, if there is a blower in your future skip them, you will just have to take them back of when you put on the supercharger, and unless you advance the timing at the same time, you prolly wont make much horsepower. Good luck.

I believe they give you about 5-7 HP increase...when I got my steeda pulleys installed I didn't notice any difference, but hey everything adds up down the road! :)

DO u also have the Steeda Timing Adjuster??? I mean, I heard that if your gonna get the pulleys you should also get the Timing adjuster..i heard u will be able to feel more power with the 2 combined! set it to 14*

Deffinattly a good mod. I installed the SLP underdrives and they are great. Have not noticed any electrical problems. I would stay away from the piggyback style that is for sure. The 5.0's seem to gain more hp from pullies but i think that is because ford has gotten smarter when the developes these things on the newer cars. Still i notice a bit more pick-up. Quicker revs

They are a great mod cheap easy to install and add a good amount of power, i had them on my 4.6 f150 for 3 years no problems. only thing i noticed was my a/c wasnt as cold. But f150s dont have e-fans so once i got rid of my stock mechanical fan and added 1 14" and 1 16" fan my a/c was nice and cool again.