While the gear box is going to change at the same rpms, regardless of the engine rpms, there is nothing to be gained by raising the rpm, that the peak torque is produced at. Unless it is fitted with a manual box, that could run into the higher rpms.
Increasing the valve lift is really the only thing that will increase the torque, and the acceleration, without resorting to pumping more air in. The valve sizes are big enough for the cylinder size, the ports are fine as they are, and the inlet and exhaust tracts are well suited to the overall design.
I think if you want to increase the preformance, you will have to forget the interferance design, and use bigger valve lift. Breaking a timing belt, though not unknown, is not something that would worry someone, that wants to get results. I would just replace it at a half distance. Most high preformance engines are interferance, just no way around it. If you are that worried about it, you should stay standard.
The lift now is 7mm inlet, 8mm exhaust, I think the difference in the lifts, is to do with the noninterferance bit. The inlet valve is 37mm, the exhaust 36mm. This looks like the bigger inlet would hit if given the same lift as the exhaust. I think the ideal cam to use, would have the same duration, with the inlet cam lift increased to 9mm.
This would keep the cost down to just two cam regrinds, instead of four. The results would be more torque, everywhere, an increase in HP, and the Inerta and Resonate tuning would work the same, as he duration remains the same.
The cam grinding can be done by reducing the base circle, or increasing the lobe height. If there is no lobe clearence problems, the latter would be the go. If there is a problem with the taller lobe hitting the sides of the follower well, reducing the base circle and fitting a 2mm shim under the follower would have to be done.
Nothing ventured, nothing gained.
Harvey.
