Ok, my own experience. Cut the mid box, fix waja 1, cuz bigger and straight.
Is waja mid box not cat conv.
Cut the tail pipe starting before the coupling. Fit 2" pipe with imitation branded exhaust such as 5zigen or apex, must imitated 1 cuz they are not so silent. Rule of thumb: 2" can support till 200 bhp.
Fuel consumption, RM10 = 52km at middle ring road II running. Traffic jam may lesser on the kms..
How I know? I tried this, From run until dry, stop at road side, put RM10 run until dry again. Haha.
Very loud, can hear in a walking distance of 7mins away straight road.
Idle time sound like boxer. High rev time will get what u want as u describe.
Anyway, I mod it back to more conservative after a couple of week to have better fuel consumption, cuz most of the time I running at MRR II. and also want to enjoy my ICE.
The pick up from 80kmh to 120kmh is in seconds, drink fuel also in second. Max speed is only 135kmh.