ok some things i found after experimenting with the car.
engine:
no oil change gives more hp for the pp. as was in gt5, and you cant undo or remove that.(only by driving the car a lot i guess)
if you need more torque overall use the chip but less hp for the pp. as was in gt5
racing exhaust will improve both hp and will shift torque high but again, without it you get more hp for the pp.as was in gt5
same goes for the other tuning's manifold etc.
turbo's do a great job, the high rev one gives better hp/torque for the pp. as in gt5.
in order to benefit from extra torque and less hp for the pp, you need to modify your gearbox and shift accordingly.
if you add ballast, you need the extra torque to be fast, specially in tracks like this one.
when you use the power limiter heavily, you produce a flat hp response at a bigger rev span, sometimes beneficial.but in order to keep the line flat in higher revs, torque drops too.
weight reduction will give more hp for a given weight when re adding ballast.same in gt5
wheels-aero:
big rims are a bit faster, seems the car handles better specially with loose suspension .new in gt6
aero don't know, didn't play with that yet, but I guess its like gt5.(better grip less top speed)
suspension:
high nose, low tail is fast.same in gt5 pre patch.
super loose shock and spring settings are fast.same in gt5
something weird that i noticed: i kept changing shock and spring settings, and didn't see or feel much of a difference.(with the pimp ride as a standard).was it me being drunk? or is something loose in there?Anyway that's new to gt6.
transmission/lsd :
higher accel numbers, seem faster than what was in gt5
moving ballast, and torque ratio towards the back seems to be faster, provided that you can handle it.
all these things probably you all know, probably better than me, the question is: where is the new and improved physics model PD was and probably is still boasting about?
these are some humble findings, no expert tuning advice, please correct me if I'm wrong, and feel free to comment and add your own findings.
ps. eclipsee is giving yinato a hard time at an amazing .002 !!! WOW Ramon!!!
Now, if I could only drive the monster which I have built. 
) and it's given me a few extra hp.
but it's pretty well run in now so probably got most of the hp back.
