Just an idle thought, what do you think of making a minor tweak to the dual overhead cams of the 16 valve engine. I don't know of any adjustable gears for the B234F engine but one could achieve a step change in timing by rotating the cams +/- a cog when installing the timing belt. Intake and exhaust could be done independently. I'd be willing to sacrifice top end power for low end torque where the engine spends most of its life - as long as it did not lead to burnt or bent valves or excessive pollution. Would the idle go rough? Any rules of thumb out there?

Bill