Here are some additional values for the Horsepower modifiers. It will depend on how much hp,you have on the current car in the garage.will add more value as i find and test them
Power Multiplier
NTSC-1c041208-1456xxxx
PAL -1C04BB08-1456xxxx

values -(boost)
1456e500-(0.7x)this reduces power by .7x)
1456eb90-(1.1x)
1456eb00-(1.2x)
1456ea00-(1.5x)
1456e990-(1.6x)
1456e900-(1.7x)
1456e890-(1.9x)
1456e800-(2.0x)
1456e200-(3.5x)
1456d900-(3.6x)
1456d600-(4.5X)
1456d400-(5.0x)
1456d300-(7.5x)
1456d100-(8.0x)
1456089c-(9.9x)
1456f300-(15.7x)
14555900-(38.9x)