The LA 15 will definitely fly the Flite Streak - especially the Top Flite ARF version which has been lightened up quite a bit. Try it on 52' lines. The perfect choice for the ARF Flite Streak has been the now discontinued OS FP 20 with a stock muffler (the 2030 version with the internal baffle cone), an APC 9-4 prop and Sig Champion 20% castor content and 10% nitro fuel. Use a green Bruline air filter over the venturi and set the needle for a wet 2 cycle.

Much has been written about this setup on other forums (some pro, some con) but everyone who has tried it (including me) swears by them. So much so we have driven up the prices of used examples on eBay to the stratosphere. But, you can buy a junker 20 FP and still get replacement parts through the distributor to bring them back to new specs.

The 2nd choice would be the LA 25 engine. Note that Brodak will be releasing a 25 engine which will be a smaller version of their Brodak 40.

I've also flown a Fox 35 on my kit built Flite Streaks and they are satisfactory - but the FP 20 is perfect.