Just picked up a 07 GT five speed with a Saleen Stage 1 blower. That was put on by JDM Engineering in Jersey. Day one boost hit 8 psi no problem held steady untill you let off the gas day two hardly wants to hit 4 psi and the boost gauge flutters like a butterfly. Car still seems to be running great but it just weird i know it should hold steady... Anyone have and ideas or info on what i can do to fix or check? All help is greatly appreciated... Thanks
another problem may be if they didnt upgrade the spark plugs and may be blowin out the spark under hard acceleration, i have my plugs gapped at .30 and anything over .35 maybe causing that
You should pull the plugs and make sure they are the colder HT0 not the stock motorcrafts. the other thing would be to check the color of the injectors they should be BLUE at least. those are generally the cobra injectors so it makes sure you have pleanty of fuel.
Belt slip could be the issue also just a loose boost line if it is not electrical. the saleens use a sender for that stuff so it could be bad.