K...Set up my Golf R and GTI to B500 and did a couple races.
All mods are stock unless otherwise noted.
Golf R mods: B500, 287hp/275lb-ft, 3153lb, 54% front
Sport Air Filter
Sport Exhaust
Street Flywheel
Race Brakes
Race Springs and Dampers
Race Clutch
Street Transmission
Race Differential
Tune:
Tire pressure 32.0 PSI front and rear
Alignment default
Spring rate default, ride height reduced to 4.7" front/4.8" rear
Damping default
Braking default (though it seems to be a little heavy on the front brakes with 50:50)
Differential: Front 0% both ways, rear 0% both ways, center 50%.
Went and completed the Golf R Spec race, won easily. The car was rather neutral and predictable; oversteer on braking into corners and lift throttle, slight understeer on power, gentle transition from oversteer to understeer going from brake to throttle. No power oversteer at all, however I could do a short 4 wheel drift if started going into a corner...but the front end would always pull out. I'm going to play with the torque setting on this car, I have a feeling that 60% rear will reduce understeer under power while remaining fairly neutral.
GTI mods: B500, 299hp/297lb-ft, 3198lb, 63% front
Race Air Filter
Race Fuel System
Race Ignition
Race Exhaust
Race intercooler
Race oil and cooling
Race flywheel
Race brakes
Race springs
Race anti-roll bars front/rear
Street clutch
Street transmission
Race differential
BBS RE wheels
Tune:
Tire pressure 32/32
Alignment default
Anti roll bars default
Spring rate default, ride height 6.4/7.2
Damping default
Braking default
Differential 0%/0%
Results: Car is a little unpredictable, tail happy under braking and coasting, lights up the front tires on throttle (299hp though) and is much more difficult than the R to hold a line, despite similar suspension setup. Transitions from understeer to oversteer smoothly on lift throttle, transition the other way is much faster. Setting the diff to 50% on acceleration definitely helps get the power down coming out of corners.
Something worth noting is that in this game, the weight between the two cars is wrong. The mk6 GTI in Forza 4 is a 2010 2dr with sunroof, weight listed 3265lb. The Golf R is a 2010 2dr base, weight listed 3188lb. With the above mods, it's still lighter than the GTI by a fair amount. According to the VW site...2013 Golf R 2dr 3325lb vs 2013 GTI 2dr Convenience/Nav 3034lb...
BTW, anyone have Forza 4 and interested in getting into some VW/Audi/Porsche spec races?