I've Owned From New a 1996 SVT Mustang COBRA. (Still Own)
Has little over 62,000 mile's so-Far

Change to Factory Header's to STAINLESS-STEEL (Made by Ford) Susposed to Add 10-12 More Pony's. Stainless-Steel Locking Header Bolt's.

Mega-Flow Stainless-Steel Muffle's Susposed to Add 8-10 more Pony's.

Use Mobil-1 Extended Motor Oil say's good for 15,000 mile's.

Split-Fire Spark-Plug's.

Averaging 27-28 M.P.G.'s on the Highway when I visit my Son (625 Mile's apart) I get 29.67 M.P.G.'s I use Ethnol Gas 10% Grain Alochol 91 Oct.