Best is the kind that puts the MAF and filter into the fender but instead of moving the MAF, one that just puts the filter into the fender is fine. If you are talking about a heatshield... just look at different available kits and see what is out there.
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 ****.