are you looking for more cornering traction or straight line ( launch ) .... for both id say go with a better tire with a lower UTQG somewhere in the 100's or lower .... now for straight get a smaller rim with more sidewall ... that will allow more grip on the launch .... for cornering ... get a wider tire ... overall youd be best off with 205/50/15 with a UTQG aroung 150 or lower
Uh... call Intercrew and ask them. They can get the Z10 bars in. The link is in my sig. Tell them that Michael sent you, and they might be nice to you.
If you want more traction, definitely get the traction bars (unless you're running an H22 engine, they won't fit), get better tires, and get an LSD if you're not averse to the price/trouble of putting one in.