hi bought recenlty a JDM supra twin turbo R so its a 1jz and after a week of normal driving i went to try it out at the track and bam there it started...bigg backfire when i let go off the gaz and biigg lagging and bogging at more then half throttle... my friend says its a leak but i doubt it... maybe its the gaz so i have to go get it tuned for the canadian gaz ??? anyways help and comments needed 
