Mine did too when it was stock. I only went that fast because i saw a 99-04 Mustang GT and a LT1/LS1 WS6 playing, not sure which one though.
I was on my way home from L.A. and it was like midnight already. And i see those two car's fly by. I was going like 70, they had to of been going like 100+mph. So by chance "there was a van going slow in the left lane passing a car", and the two car's were right behind the van. I instantly caught up pacing speed at about 70. When the van moves over to pass the car in the right lane. I see the WS6 on the GT's ass, so i dropped it down to 4th gear and ride the WS6's ass, the GT pulls into the right lane and we both pass the GT slowly and I'm inching closer reeling in the WS6. I look down, were at 135mph! He then moves into the right lane and i slowly walk pass him at 140+ and continue to slowly pull.
I look at my speedo. It was like 150-151, I look in my rear view and he's only like 2-3car's back in the other lane, not that far back! I Just let off. Could of gone more but just gave up since i pulled!!
BTW: My car felt way faster when it was bone stock. Then i decided to get the Reflash and noticed how slower the car was. Now my car with the mods i have listed, feels the same as when i had the car stock. Think i had a Factory Freak, i mean it pulled hard all the way from 0-120+. I notice how this car run's out of steam in the top-end but it doesn't.
When i was stock, i also held neck and neck with my friends 06 350Z 6spd from a Roll, he had Intake, test pipes, plenum spacer.
MS6-Stock
350Z-Intake, test pipes, plenum spacer
Now with the mod's listed i have, he hangs and pulls on me by couple feet after 120. With the 2 extra mods now
MS6-Intake,Test pipe, BOV
350Z-Intake, Test pipes, plenum spacer, exhaust, Nismo Header