Dudes
I have a 2011 Neo R3 bought in March 2011 and spent some time doing tests and concepts. I would not recommend boring the Throttle Body unless your engine is the older Campro DOHC without CPS and VIM/IAFM. You will find that it does not make any difference. If you are trying to mod Campro engines fitted with IAFM or VIM, please leave half of what you learn from Mitsubishi/Honda engine mods at the door.
Major difference is that VIM/IAFM is activated by ECU at around 4500 rpm. IAFM uses vacuum line, a cheap alternative but not necessarily bad compared to VIM. It uses a short path for high rpm torque and a longer path for low rpm torque. It is the single reason why you don't have a torque dip at 3000 rpm. The short runner comes in and the resonance effect increases torque.
Think of it a a plenum chamber that changes size at 4500rpm. Changing the VIM chamber to a fixed plenum will make the torque dip return.
This is a fly by wire system where there is no physical link between throttle body and accelerator. The Oxygen sensor at the exhaust and the MAP sensor at the intake plenum plays more vital part in the fuel injection and timing retard/advance. If you bore the TB, the MAP sensor will report changes and in later engine runs, the ECU will relearn and see the new air intake pressure and change the timing advance/retard.
The best bang for your money would be to fit the intake snorkel from Campro Neo. Yes the older version. There is significant restriction in the intake of CPS cars (all version). I think it is to reduce noise coming from the engine. The bigger size snorkel will help to reduce restriction on intake. You will not get a power increase but it will make your engine more responsive to accelerator input. Somehow I've managed to get better FC at low engine revs around 2-3000rpm coasting flat. Recorded 4.7l/100km as compared to 5.3 before.
The next best thing is to get a proper tuned exhaust header. Get one that has a large turning radius and really tuned. The cap ayam ones are only good to reduce weight and nothing much. A really cap ayam one will make your power + torque fail. Nothing beats a good engineered solution.
If you have the money, change the gear ratios and the final drive. IMHO this is the jewel of the Neo R3. It is sweet.
If you really need to have quad throttle, know that it will not solve the inherent torque dip. If you have them, its good for drag runs from more than 3000 rpm. Keep it in the high revs and it should be pretty happy.
A new fangled coloured intake filter does not make much difference. It was good for carb days. You really don't need to change it.
Good luck in your modding days!