4th gear? knock?

[asd_gst]

in my 91 gst when im in 4th gear boosting around 7-10 psi according to the stock gauge but i know its not accurate, at speeds around 70mph give or take a few the car seems to shutter im not sure if its knocking dont have anything to check it with. but i still have the stock smic i think that is why im running 93 octane, all stock besides k&n air filter, hacked air can, and bcs removed... so is this normal?

 

[PIMking]

well you dont know how much boost your boosting. get an aftermarket gauge. and you wont know if your knocking with out some type of logger. You sure you dont have a boost leak?

 

[asd_gst]

im not positive, the car was doing this last week but it was in 3rd gear too but i thought it was boost leak or something, but it didnt start till i got gas from a gas station then i thought maybe bad gas changed the gas it stopped or at least didnt shutter as bad when under boost, but it doesnt do it in 3rd as bad but 4th you can tell...