Thats what i had...many years ago...boosted my S2 to 550 bhp...
yes it was a fekin animal to drive and a bitch to live with.
Running on optimax with two bottles of millers additive to stop the engine pinking.
needless to say whilst i did get that power out of it...it was short livied so dropped it back down to 340 mark to get some useability out of the beastie.
I spent 1000's on it...and in the end sold it for a pittance...god i miss that car!
I know the feeling, a fortune, blood, sweat, heart and soul, and for a pittance lol