I was having a little play with a JDM Civic Type R with supercharger last night. This one puts out just over 280 bhp, and bare in mind it is FWD so, the power losses are only around 18% ! I was pulling very slightly from him up to around 120 bananas and mine is running under 1 bar with tmic, 3" elbow to 2 1/2" system and Apexi filter. There is defo something up with your car. I can leave lightly modded CTR's very easily !
Cheers
Paul