Coyote - not sure where you are getting your info, but the 2008+G37 is rated at 330HP - not 225 as you stated in your post. That's why on paper you would think it might be a close race. However, take a look at the torque - the G37 has a paltry 270 Ft/Lbs compared to the SRT6's 310. That additional 40 ft/lbs makes a huge difference in a race!

Before the SRT6, I owned an 05 G35, which was only 298 HP and 258 torque (dynoed 254 HP, 226 torque at the wheels). I raced my same friend in the same type of race when he first got his 09 G37s, and while he ended up edging by me, the race was pretty darn close. Those infiniti's are only mid/high 13 second cars, and I doubt a cold air intake will give more than 5-10 HP, which isn't going to knock a half a second off to get it down the the SRT6's low 13 second capability.

Even if the exhaust mod slows down the SRT6 a tenth or two, I would wager that it will still win fairly easily. My buddy with the G37 refused to believe that my SRT6 was stock because I walked away from him so badly.