If you want to fly 3D then *forget* the SuperTigre it's just not up to the job of providing the flawless throttle-response needed for good 3D flying.

With an all-up-weight of 6.4lbs, I doubt that *anything* less than a .90 will provide the level of performance you're looking for.

I'd forget about .61-sized engines, they're not much more powerful than a .46 but weigh (on average) about 50% more. Most .75-.90 sized 2-strokes are almost exactly the same weight as a .61 but put out around 30% more horsepower.

A nice Saito 100 sounds like it would be just the thing for that model. Light, powerful, excellent throttle response and mid-range etc. However, they are (moreso now that prices have gone up) very expensive.

The latest crop of OS engines are pretty good.. at a pinch, the OS75AX might be okay for that model but you'll be paying a lot of money for an engine that's really at the very bottom of the power-range for your desired performance.

Thunder-Tiger (not Thunder Power) engines are very good but I don't think they have one that would be a good fit for this model. The 75FS would probably be too weak for the kind of performance you're after and the 91FS will likely be way too heavy (it's the heaviest .91 4-stroke on the planet). Forget about the .61-sized Thunder Tiger engines - like all the other .61s, they're too heavy for their power output when compared to a modern .90-sized 2-stroke.

As for you not wanting to cut up the cowl too much I can understand that. A 4-stroke will probably require much less cowl-cutting than a 2-stroke because of the smaller mufflers involved but you could use a pits-style muffler with a 2-stroke although that's probably going to knock the power back somewhat.

So basically -

A Saito 82 or even a 100 would be my first choice.

An OS75AX would be my second choice.

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