In the GT8 cars, it depends on the track. Short track with much mid to short straights a torque engine will give you better lap times. Open fast track, the RPM will give you more top. I've also used higher RPM engines on tracks with less traction, so it comes out of the corner better. But the big issue with these cars is that these cars are 7 3/4 lbs, so the engine has to be able to move it.

I have both in my box and will change based on where I'm racing. And as noted above out of the box, the Picco will be better. Send the Ison off to Murnan and you will be VERY HAPPY.