and sits at the point where i have set me boost controller too (about 9-10psi). does that for a couple of seconds, then all of a sudden it just shoots of from the 9psi mark up to about 13-14!
its ur boost guage....st165s are supposed to hit fuel cut at 12 psi...mine hits it alot earlier 10.xx..ive heard quite a few hit it alot earlier...so if it were relly spiking to 13-14 you would be hitting fuel cut..when i fit a cheap guage to mine with stock boost it would raise to 5 then after a few seconds jump to anywhere between 9 and 15...(tvsv was still enabled but it wasnt the problem)..problem dissapeared when i got all the kinks out of the line for my guage...if you wan to run a boost controller i strongly reccomend u disable the tvsv anyway...so disable your tvsv..then check over the line to ur guage for kinks and such