I have a 99 GST with complete 3inch exhaust with a 4 inch outlet. It will hit 120mph and wont go any faster. it is at only 4500 on tach. IS this a normal thing? what do i need to do to allow to go faster?

 

Thats normal for a GST. Usually i think the max is around 125-130 but it takes a while to get there. Now i must ask....why do you feel you need to go this fast. Acceleration is more important than top speed imho

 

Search this on google. Vfaq.net explains why

 

Yup, speed limiter. Mitsu used tires that were rated to 130mph, so the speed limiter was utilized in the GSTs. So, if you, for whatever reason have a need to endanger your life and everyone else around you, at least get tires that are rated for higher and get a good balance so that the tires don't decintegrate and your suspension doesn't give out and cause you to slam into something or someone.
Welcome to Mitsforums noob.

 

Ergh... I hate H rated tires lol

 

I have Z rated tires on my '99 GS-T...i've had mine over 120 and it didn't cut out...That was only ONE TIME and on the interstate at that only cuz I had a Porsche 911 comin up behind me pretty fast so I ran it up there just to mess with him until he got tired of pissin with me and gunned it, then bye bye.