I just got my 350Z with an APS TT turbo in it. On the drive back I played around with it some on some empty OK roads. I ended up getting up to 145mph before chickening out. Whats the fastest any Z owners with that kit have gotten up to, and when does it start to get sketcy stability wise?

 

I'm using the Power Enterprise turbo kit at 7.5-8 psi of boost. The fastest I've been is 155mph and still pulling(govenor is 159 I think). At that time I was racing a vette. At those speeds, it is wise to do some sort of suspension modification. With mine I have D2 coilovers, cusco swaybars, GT spec underbrace as well as there front and rear ties braces. The car handles very well at those speeds, with no problems.

 

150 mph with stock suspention. Toyo Tires 245 front 285 rear

 

154 or 155 when i shifted to 6th and then shut down

 

Your limit on the Z is not the APS TT, it is the gear ratio on the transmission. You red line in 6th before the Torque limit to push the car faster has been met, if you want to go faster - get your transmission modified.