[Bobboloo]

For what purpose is the engine to be used? Is it for a race car or for a street car?

Explain what you mean by getting tired. Are your compression numbers down?

The reason I ask these questions is that you already have argueably the best street/performance motor for a Porsche under 2.7 liters. S cams will actually rob you of the pep in the low RPM range. The E cam not only feels quicker but is quicker 0 to 60mph.

You might just try an increase in displacement from 2.4 to 2.5 by boring out your cylinders from 84mm to 86mm and installing some JE pistons to get 2.5 liters. This would not require cutting the case spigots, would be cost effective, and would be my preference for a street car rather than a 2.4S motor.

If you want some real torque then cut the spigots to 97mm so you can by a set of 93mm Mahle P+C's. This will give you a 2.9 motor but will require reworking of the MFI pump, ports, stacks and will be quite expensive when all said and done. It would probably be cheaper to buy a 3.2 and install it.