Well I'll be using TWO of them so I'm good for 2.6 liter, or roughly, 3 of the 8 cylinders!
Surprisingly, even with the air filters you really can't "feel" a loss of horse power. I suppose it could be measured via a drag strip run, but on the street it's not really an issue. I can easily overcome the 10" Goodyear sticky slicks in 2nd gear if I get on the throttle to hard. With or without filters, regardless of jet size's. You can only hook up so much power, after that, it may come in handy for top speed accelleration, but it matters little in first or second gear.