i have seen some ETS kits dyno about 50-70whp less than they should. these werent there twin scroll kits or any of the HTA’s but still. also there intercoolers arnt as good as the Buschur unit.
i have done my time (4 years) in the evoh world and buschur and AMS are #1. i would say buschur parts are less engineered but work just as well if not better in some cases.