I don't really chasing for power or chassis or what so ever with the hybriding although I do want some power, the game's just not giving that much feel of going fast so I haven't bother about it...
so what I did was put a real shift mech to each of premium car... for ex: mclaren MP4-12C have a dual clutch gear but in the game it act like a manual with clutch, so what I did was hybriding SLS AMG gear mech to it (I've tried blending California's gears for its short ratio but it didn't work).... my god the cars just transformed into something different... also I tried the SLR which in real life is an 5 speeder automatic, but in the game it reacts like, you guessed it, a manual with a clutch. so what I did was putting SL55 AMG shift mech (turns out to be the same gearbox, torque converter 5 speed auto), the result is spectacular..
I'll give the list of all the car that got a different shift mech in GT5 and what they need to make them got a real shift feel(premium only, haven't tried the standard car and gear ratio is totally different but you get the point

)
Audi:
- TT 3.2 V6 quattro '03 = S-tronic dual clutch so hybrid them with R35 GTR shift mech
- TT 3.2 V6 quattro '07 = the same as above
- TTS coupe '09 = the same as above
- RS6 V10 '08 = 6 speed Auto so hybrid with ISF gearbox
Dodge:
- Challenger SRT8 '08= 5 speed automatic so hybrid with SL55 gearbox
Ferrari:
- 458 Italia= 7 speed dual-clutch so hybrid them with California's gearbox
- 430 Scuderia= 6 speed automated manual with 60 ms shift time (very fast shift) so merge with California's gearbox
Mclaren:
- MP4-12C= 7 speed dual clutch, hybrid them with SLS AMG's gearbox (as I explain at first)
Mercedes:
- C63 AMG= 7 speed MCT automatic, hybrid them with IS-F gearbox (the gear ratio will be very2 long)
- SLR mclaren with 19 inch wheel option '09= 5 Speed Auto so hybrid them with SL55 AMG's Gearbox
Nissan:
- Skyline Sedan 350 GT Type SP '06= 5 speed auto, hybrid them with SL55 AMG's gearbox
Volkswagen:
- Golf R, Scirocco R: =6 speed dual clutch, hybrid them with R35 GT-R's gearbox
Volvo:
- C30 T5 R-Design: 5 Speed auto , hybrid them with SL55 AMG's gearbox
that's it for now.. hope you guys like it