I have the answer to your problems:
The difference between the Harley and the Lightning engine wise is that the Lightning has a smaller nose pulley allowing the supercharger to spool up faster. All you have to do is change the supercharger nose end on the Harley to the one on the Lightning and you have the same HP and TQ as the Lightning. I believe Magna Charger has it but don't quote me.
But If it was for me I'd get the Lightning, but if you need more room get the Harley and change the supercharger nose end.
Or if you really wanna go fancy, buy my X5
