UDP's, which ones?

Also, I just did some quick searching, and the Steeda pulleys are on sale for $199. I don't know how the quality compares between the two, but I do know that the Steeda ones are tuned for the proper harmonic frequency of our motors. It may be worth it to you for the extra $30, but I have no idea what the quality of the Moto Blue.
 
i have the roush UDPs. the instructions are 10X better than the steeda UDPs. i have installed both sets. they install very similarly, but with the roush, you trim off the unthreaded part of a stud, and steeda gives a new bolt to replace the stud. i like the trim part better, some like the replace option. other than the stud, they install the same. click the link in my sig for a good set of instructions.
 
No trouble here with my Steedas. I, too, noticed the difference right away. There is a definite low end snap that wasn't there before I installed them.