I doubt it would make it for the 2005 models, but if Lotus did offer it in 2006, I'd hope it would a retrofitable dealer option.
With a power kit, I would expect a modest power increase (less than aftermarket company claims), but I'd expect it to be a confirmed increase that was reliable and not void the warranty.
1) How much would you pay for a power kit that offer hotter cams, updated ECU, and probably revised intake and exhaust?
And, being reasonable
2) What type of power would you expect for your money.