very little, says the big converter is holding me up.. I'm aware they do soak up a bit of power but I've never heard of one robbing tonnes of power like that. I've seen very similar set ups making another hundred odd horsepower on other cars. I know it's not ALL about the numbers, it's about how it goes. but when I look at it, I made 40 less horsepower with a stock turbo AND 4 pounds less boost AND on 98 with an unopened engine.. quite disappointed to say the least. will have a chat to him about it when I go to get it touched up.. idles too low, stalls in stop/start traffic, stalls immediately after hot start etc Sent from my iPhone using Tapatalk