[Ecky]

Some disordered thoughts:

Complete kit for a 2012+ Civic Si 6th gear cost me around $200 new.

The Accord transmission has the best ratios out of the box, with a 4.4 FD and 0.659 5th gear.

TSX box has nice ratios after you swap the final drive but the magnesium casing is more fragile and not appropriate for high boost and sticky tires.

To my knowledge the Accord and TSX casings are identical, and internals can be interchanged.

I have no idea about AWD or differentials. An LSD did a lot for my car's traction.

4.0 FD from the Euro Accord is the tallest factory FD. I had a 3.4 made by Frana Motors, cost was about twice that of a new 4.0 FD.

Don't get too far from the Insight's stock offset or dimensions or you'll start to have weird effects on handling. 195/55r14 with a really sticky rubber would probably be my choice for the drag strip.

Edit: For what it's worth, even a 3.4FD and 0.647 6th gear could be taller in this car with a stock K24A2, it climbs mountains easily in top gear, no shifting at all. I would hate to have lesser gearing. Thinking of upsizing to 185/65 65 or even 70 aspect ratio to bring it down further.