“longer legs” for my type R

Hello guys, I have an EP3 Type R from 2005. Something bothers me about the car: the short Gaenge and the high fuel consumption with not once sporty driving. I mean, if I drive 180-200 I am constantly around at 5500-6000 tours and consume almost as much fuel as the CLS, which has twice as much cylinder capacity, these shynesses but loosely with 2500-300 turns from the hanklecht. I believe the simplest solution would be a lower differential, right? Is there something like that already on the market? Or do you have any address to which I could turn? With that in the ideal way would be a VTEC adjustment – at longer distances I need the other valve configuration already at 5000 turns or so. Is that possible? Can you stroll around it? thanks for your help! gruss, lennart