I have similar desires to tune my VIS.
I did the full service which costed 1000€ 2 years ago (and about 20.000km), changed the thermostat which means that it needs about 3 min to warm up to 90*C and stays there fixed, cold or hot day no matter what...
Also change the water temp. sensor also...
The VIS delivers power over 3500 range where it has the most torque,but after I'm kinda dissapointed
From 4000-6000 it does rev put it doesn't pull at all, seems like it strugling or something..
Fitted K&N box filter which didn't do any good, it maybe made it even worse....
So now I wanted to have more "power" from my VIS the first step should be exhaust and Remap from FCS?
I do however have 18" ultaleggeras installed which weigh about 18kg with wheels which I think is not that much...I would swap for 16" orginal 20vt alloys but the grip on 18" is much better.....
Also cleaned the MAF sensor but I didn't do much difference.....I would buy new one but I costs 100€ which is quite expensive if you consider that I might not change anything....
Still angry when the Coop doesn't pull as much as I want in high revs, it makes overtaking cars hard and risky...
With my ex chiped 16VT it was much easier