I can't speak for mileage improvement, but I get 15 average in my 68 Charger 512cid,a518 w/lock up & 3.23 gear 28" tire.


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5