Rudeboy

You cant' build a laminar flow wing by hand... You just can't achieve the accuracy that is needed, unless perhaps you spend 2 years shaping it to perfection with laser cut gauges.
Forget laminar flow.

If you are looking for straight line speed, start by making your wing only half as thick. 1" is way too fat.
Build a decent fuse, instead of a square box.
Use a rear exhaust racing engine, and cowl everything. If you insist on side exhaust, at least cowl the engine as good as you can.
Airfoil your tail.
All internal linkages.
Loose the landing gear.

If you use a Q500 muffler, you must prop the engine to run at Q500 rpm: at least 19000 rich on the ground, preferably a bit more and unloading in the air. I don't know if the SJ50 will support that though...