anyone currently using the BBK 15550 underdrive pulley set? what , if any performance or MPG gain did you notice in the real world driving experience? any other pros and cons with this set? i have a 2003 5.4L FX4.....

 

Maybe the guys with those engines will know.

 

I have the 3 piece set on my 98 5.4 Expy EB 4x4. I can say that on avg. the gas mileage increased some. Before I used to get about 290-300 miles to a tank in the summer. (95% city driving) After installing the pulleys the mileage went up to about 310-320 at best under the same driving conditions, (i.e. same routes taken, and filled up at the the same station with the same grade of fuel.)
My other mods are listed in my sig., They were already installed prior to doing this mod.
The only cons about these are, my interior illumination sometimes dims ever-so slightly when coming to a halt. I suspect this is due to the alternator putting out a lesser amount of amps due to the pulley. The other con of this was the install instructions were kind of hard to understand at first. Since BBK sends you a universal kit for a wide variety of 5.4/4.6 applications, they neglect to mention what needs to be done at certain steps. So be careful reading the instructions when installing this kit. Or better yet give BBk a call and talk to someone in their tech department to get a clearer picture of how to properly install the pulleys.
Overall I would say that these pulleys are worth it, at least for me they were.($150 spent) The truck feels alot stronger in the upper rev. range, and highway passing ability has improved. Oh, and I was also able to break the 265/70/17's loose in 2wd mode for the first time on dry asphalt!

 

anyone else have experience with these, or other pulley kits?

 

OK, so i'm looking at the BBK 15550 kits...but, if you look at these two links, one appears polished, yet they are both the same part number???? anyone have any experience with these and now if one is truly polished?

http://store.summitracing.com/partdetail.asp?CP=1&part=BBK-15550&N=700%200&Ntt=BBK~15550%20or%20ASP~528774&Nt k=KeywordSearch&rsview=sku&Ns=

POLISHED??? http://www.sfxperformance.com/parts/BBK15550.htm

according to BBK, they should be polished?
15550 - 3-piece polished aluminum pulley kit

just wondering if summit racing has old stock??? they don't look polished.

 

They are the same thing. Mine didnt look too polished when they arrived. They looked like tey had just been cut from an aluminum billet before being shipped to my door. There should not be a difference between the kits as far I know. If anything most of my 'Stang driving friends said that it is a good idea to give the pulleys a little scrub with a steel wool pad or something similar to prevent glazing when you install the new drive belt. Anyways, IMO these kits are the same, just the camera techniques/settings used to take the promo pictures are different.