DO NOT BUY CHEAP SHIT EBAY ONES
buy either tial or turbosmart , turbosmart are more expensive so i would personally buy a 44mm tial wastegate , ive used one on my 522bhp engine with no probs and i know alot of people running tials and they are fine
i got mine from looseboltsmotorsports in the usa for around £280 compared to the £450 uk stores want

hope this helps

cheers paul