Speed Freek. Since nitro is expensive out there I would recommend the Fox .61 modified with remote needle if you like. It was the strongest engine for torque reviewed by MAN a year or so ago, yet the second strongest for horsepower. The K&B screw head wasn't reviewed, but it is strong and much lighter, it comes with a remote needle. There is also the LA .65 which is torqie and actually has more power than that paperweight you have, but I get the impression you want to avoid OS.