Might be belt slip. Inspect every coupler and all the piping/hoses and everything.
Not to mention you might not be happy with it because the tune could be the stock vortech tune. Its a VERY conservative tune and the draw thru setup they use with the 79-04 MAF element is crappy.
Ever since the 05+ slot MAF setup came out, that is the way to go with a forced induction app, and blow thru. No more bypass (BOV to open air), way easier to tune for and more accurate.
But keeping it simple, look for a leak first.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.