I hear you on the Contisports...I have those on my Vantage...good tires but I can't get them off the line cleanly. Once things get rolling they are just fine, but first gear is useless if I'm too hard on the throttle. My best runs have actually been with starting in 2nd gear.

Another option for the X5 is the Dinan chip...610 hp and full warranty. Top end on this car is never going to be as good as a sports car or even a powerful sedan...not even just power to weight but aerodynamics and drag. It's tough to cut through the air at 150 mph with such a large frontal area. But for its size, weight, and utility, the performance is shockingly good.

I'm ditching the run flats on the X5 this week...I bet regular tires are good for at least 2 tenths of a second improvement in the 0-60 and 1/4 mile...we'll see.

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2017 Nissan GTR Red/black - Tune/midpipe
2013 BMW X5 50i M-sport Alpine white/black - Dinan stage 1
2016 Jaguar F-Type R Gray/red