Do you have a full catback or just the mufflers welded in? If just mufflers I would recommend the full catback whichever route you go. SLP will be the meanest sounding of the lot from my experience. However, you may want to invest in something that will actually make the car go faster vs just sound mean.
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 ****.