With Tires speed rated for 168mph and the well publisized notion that Top speed is
five(5) miles below rated tire speed. I've been to both pontiac and cadillac dealers,
Pontiac didn't know, Cadillac stated 155-160, with cutoff occurring after, (1) reaching 155-160, (2) Reaching close to peak and then coasting for 1/4 mile, the throttle will cut off. Is ther any verification out there, other than risking the blue lights? I have both
03 SSEI and 04 GXP - As an enthusiast all i can say is awesome.

Not sure exactly But I think there is a US law that "average" US made cars must be limitied to no faster than 155mph. I think for imports too all must be limited to 155 from the factory for US sales cars. I bet that highend exotics and others don't fall into this rule and of course there is ways around this.

I believe my 01 SSEi was limited at 138 I think, but now with the Intense PCM it'* been raised. In the programing their still is a limiter value has to be entered, it just gets raised to an unreachable number for us. Like set at 199mph or along those lines.

The limit in the 00 SSEi is 128 mph, thats why you have H-rated tires.

Its the tires that determine the max speed (governed) anyone that lifts the governor on any car must realize that upping the tire rating is necessary. Sustaining speeds higher then tire rating is dangerous.

I will bet the GXP is governor at 135mph (granted it came outfitted with V-rated tires) but seeing the Eagle RSA'* on the GXP, I bet the governor kicks in at 128mph

Backwards there, you have H tires, and that'* why your limiter is 128.

All passenger cars are 155 if you look at top speeds of uber-sedans in magazines, they're all limited @ 155. Not like anyone will stretch those legs anyways...

According to my latest Bonneville subscription mag from Pontiac, the top speed is governed at 135mph. 0-60 in 6.5 sec. Other sources say 6.8sec, but I believe GM and Pontiac personally. My 02 SSEI has hit about 135 and that was pedal to the floor and on a decline on a clear road. Now thats according to my HUD. After I saw that speed I put my eyes directly on the road and began to slow down. The guy behind me said that he was pushing 130+.

According to the Sept,04 Car & Driver(the first road test of the GXP in a car mag that I know of)the top speed of the GXP is 141mph(non-governed),...which is 11mph faster than the Hemi 300C tested in the same major article,which was governed at 130mph.The GXP is not nearly as quick as the 300C......but if you 'hang on'long enough(and have enough highway real estate),you can walk by the Chrysler.

Like some Cadillacs, which have the same engine as the GXP, they will go in the 140'*.

Its all in the tire rating.

I say any V6 or V8 should be standard with V-rated meets from the factory

In the case of the GXP'* top speed it doesn't have anything to do with the tire rating,....the car gets up to 141mph and that'* as fast as the car will go[given it'* particular engine powe]r,limited by the air drag,rolling resistense,drivetrain friction/resistense,etc.

Most cars are capable of speeds in the range of 150mph+, the governor is put of the speed because of the tires that are on the car, any H-rated (passenger tire) will have a governor at 128 mph, any passenger car with V-rated tires is governed at 140mph.

Engines are capable no doubt, thats not the point I am trying to illustrate in this case.