[Kincurd]

My slightly ecomodded car averages 37.5mpg in another driver's hands (slightly above factory rating of 37mpg). When I drive it, I get 47.7 mpg (at least the last tank I had on it was that.)

I think Ecomods more or less compliment the hypermiler. It's like installing a super-charger. Technically, the supercharger will increase MPG under the hyper-miler's gentle touch, but will kill MPG with a heavy foot.

Aerodynamics and lighter weight allow you to accelerate faster, so maybe you were adjusting to these changes more like a racer would, than a hypermiler?

Ps. Also, yeah, any tweaking to the exhaust (like removing the cat) is kind of funky. Street-racers and wannabes always target the exhaust and I think some of them simply slap on a wider opening muffler without much regard to back pressure and such.

The only exhaust mod I'd feel comfortable with is extending the muffler slightly out and tilting it for streamlining purposes, and replacing the muffler with an exact replica made of lighter materials (like aluminum or oven-cured Carbon Fiber).