JC I know the roads you mention only too well . Lived in Mandurah up untill about 9 years ago and have family in Muchae . Anyway My BF 6 speed manual is also heavy on juice and has 324.7 at the back wheels . Drove from Adelaide to Melbourne for the FPV open day in March with an XR8 (FG) . XR6 (N/A) , F6 (BF) (mid 300 rwkw) and a Devil R . No matter what we were doing mine was always well above all the rest other than the N/A XR6 as he had the club trailer on . I can get high 9 to 10 on the open road and 14 to 15 in the city . Yours at 20 sounds a bit high but that can depend on how heavy your foot is . A good tuner can lean the car out for you but dont go too far as you can harm the motor . This is the price you pay to feed the need for more power (its great fun) . I have the Pole possition tripod and have no issues with it . With your engine management light on I would guess that the 2nd O2 sensor has not been switched off . You are correct a good engine tuner will switch this off , should be done once you start playing with bigger boost as I understand it . Otherwise the light just keeps on comming on . Get a mechanic with a camera to look at your cat , with the higher power the factory ones melt on the rear side generally . You may find this is the issue with your ecconomy . When mine was being retuned the last time we got 327 at the rear then couldnt get over 190 . On opening the cat up we had melted it to a solid mass . Exhaust now fixed and boost fine tuned to give a great strong even curve that makes tyres wear extreemly fast (not ripping skids I might add)