That is exactly the range I saw improvement in. I got 20 on a trip to Dallas right after. Haven't done much since, I just got them in a few weeks ago. My old cats were almost totally plugged. It was sick. The guy that had it before me did not take care of it.

 

TWENTY MPG IN A DISCO! WOW! I'd never dreamed of such numbers. That would be about a 70% improvement on what I get now. I've been as low as 10.5 mpg around town. The cats would pay for themselves in a just a few fill ups.That's great I'm really pumped up about doing this now! I just had a hunch that the engine was being stiffled by something, just by the feel of it. It feels justlike a two stroke motor when the exhaust is plugged up with oily carbon. (I used to work on two strokes a lot) There's a Magnaflow dealer (Mustang shop) just down the road from me and I spoke to them about doing this. The guy in the shop said the Magnaflow cats will last longer & be less prone to clogging compared to the OEM LR ones. He said you can see day light through them when you get them.

Unfortunately I don't think I'll get the time to do this for overa month as I've got too much going on July. Anyway now I know what direction to go in. Thanks okdiscoguy! If you're in Dallas again sometime email me before you come & I'll buy you lunch if you have time. Email: mordor110@tx.rr.com