Mr 19", Got it now, thinking it through the inlets that flutter as the springs try to close the valve against the boost rushing in against the valve. As to why rev it more, well because I can, the engine is so short stroked as standard that it's a crime not to let it rev like it want to.

I may be running standard short duration, low lift cams but power is still climbing rapidly and from the torque curve it looks like it's going to be worth going to 7300 soft limit 7500 hard. If that is the case then we can twiddle with the boost map to give around 400bhp all the way from 6000 to the 7300 redline, to give a monstrously grunty and flexible top end without compromising driveability.

If I were going to fit bigger cams then I'd also get the valve seats recut for bigger valves, the porting that I've already done is going to be fine up to 8500 but at 8k the standard valves will start to be a limiting factor.

So what we're saying is that standard rods, bolts, tappets etc are all good to 8k, it's just the springs that need swapping. Superb, thanks chaps.