Its not worth $20.
Your one and only MAF upgrade should be to a slot style (05+) MAF when/if you ever go with a power adder. That is a one time buy and a basic aftermarket one will support up to 1200hp depending on sample tube size.
Like so many things for these cars, the "performance" MAFs are snake oil. Nothing you bolt onto a 99-04 besides exhaust is going to do much for power. If anything. Maybe plenum and TB for a few hp, that's about it.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.