right people i thought id post a bit of a tuning guide for the 105/120 as it seems like the car most zr owners tune the most.
1- cat back exhaust system (janspeed,blueflame,powerflow etc) £250-350
2- janspeed 4-2-1 manifold £180
3- janspeed sports cat £240ish or the de cat £80
4- 52 mm...