David, I've had the UR "Ultra-S" small diameter crank pulley on my car for over a year now. No problems. FYI: No other underdriven accessories, just crank is all you need.
I spoke to UR directly when I bought it and they claim 5hp just from the crank and better gas mileage. I can't say how much if accurate for sure but most likely underdriving the crank will help. No problem with charging system either.
I am looking information about Aem tru-power pulley because I am interested in use on my accord 4cyl. do you Feel enough difference using this product?Need opinion and suggestion !!!
i saw a dyno sheet on a stock accord again 5hp to the wheels aem pulleys. i got them on my car the first day i did notice a differnce it will take off faster
Basically the issue is you loose the harmonic balancer (going back a few posts). Also, i do remember reading a comparison to lightweight non underdrive pulleys, compared to stock and underdrive pulleys and the gains were very minimal so it seems pointless to me to just go with a lightened one. That is from reading though, not personal experience.