Im considering putting a 100 shot on my car but I know the stock pzero's wont be able to handle that much power. You guys think my car would look wierd running the stock tires up front with 245/45 nitto 555r's in the back on the stock 17 inch rims?

 

That tire size is going to throw your speedometer off (and your odometer too)...a lot, like 43 wheel revolutions per mile. You're talking like a 4 mph difference at 70mph. If I were you I would go with 255/50 R17 where it will only throw your guages off by 3 revolutions/mile or 0.3MPH at 70. 255/50 is harder to find but not only is it going to have less impact on your instruments but it will give you more grip.

And yeah, 245/45 would look wierd. Stock sidewall height is 5.1 inches and the size you're talking about is 4.3. Your rear axle would look like its squatting.

 

Consumers Reports did UHP tire tests in the Nov. issue. Although the Mustang's stock Pirelli P-Zero M+S all-season tires did poorly, the Pirelli P-Zero summer UHP tires tested were second only to Michelin Pilot Sport PS2. Nitto's NT 555 extreme zr didn't do well but I don't know if that's the same tire you want to use. It's interesting how one tire with same name but different classes can be so different in testing results.