[PeteKz]

Rich, here's what I wrote in another thread a couple months ago:

"Back to the M1 cam: I haven't got my car on a dyno yet to do the final tuning, so I don't know what the numbers are. I will post those after I do that. That said, I do know from my measurements as I timed the M1 cam that it uses all the room available for lift and duration on 3.0 and 3.2 engines without the valves hitting the pistons. Therefore, one has to stay very close to the recommended cam timing, because retarding or advancing the timing more than a few degrees, WILL result in cam/piston interference. I measured that. So, yes, "it leaves performance on the table" IF you want higher RPM power, but are willing to give up low-mid RPM torque.

If you choose different pistons with valve pockets, you can choose a more "radical" cam, but you will give up low RPM torque and smoothness. As Henry observed, to a racer, high-RPM power is most important, but a high-RPM engine is a lousy street driving experience.

What the M1 does for a street car is give a wide range of torque. As I noted before, I have retained CIS on my car, and I can floor the gas pedal at just above idle, in the higher gears, and it will pull smoothly all the way to redline. I like that for a street car, especially with the crappy-shifting 915 transmission. I also get close to 30MPG at constant highway speed. Not shabby for an old engine design. Even if I don't get to my desired 230 RWHP @6000RPM in my tuning, I like the driving characteristics enough that I would build another engine with it."
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Therefore, if you plan to stay with the pistons designed for the 3.0 or 3.2 engines, use the M1 cam because it was designed to get the most out of these pistons. Given my measurements, I don't think it's possible to get any more without piston/valve interference.

If you plan to change the pistons and cams, you have to pick your tradeoffs. To get more power, you WILL reduce low speed torque and smoothness, and make it less pleasant to drive in traffic. Lots of people don't mind trading off some low-RPM street driving smoothness to get a more rev-happy experience. I've owned cars like that too. But the reality is I drive 95+% of my miles on highways and local roads. So I built my engine to maximize that torque, with reasonable high-RPM power, and good efficiency.

Be honest with yourself about how you will really use the car. Lots of people have built high-RPM power engines and then come back to engines that produce a fat low- to mid-range torque curve, because it works better for how they really drive the car.

If you want more details, contact William Knight, since he's the proprietor.

Late edit: If you decide to change the pistons and cams, then the exhaust system becomes more important too, so plan on buying headers or the large SSI's or something like that, along with a different muffler.