Running "lean" will lead to detonation, which can cause catistofic engine failure if left unchecked. The gas basicily explodes before the piston reaches the top of the stroke, and puts huge stresses on the bearings/rods/pistons. In a diesel, this is not a bad thing, in a gas car, it is terrible. Don't mess around. Tune it, with a sct or diablo or the like. I know, they cost money, but so does a new engine. You can get a used one cheaper on E-bay or craigslist (a tuner) but just like anything, you take your chances on what kind of condition it is in, and if it even will work or is unlocked from whatever car it was linked to to start with. The BBK is a great intake, but it really needs to be used along with a tune or it can lead to problems. Some of the intakes claim they can be used witout a tune, but if they do, then they probably arent letting in enough air to make any difference over stock. A BBK WILL outflow enough to make you run lean, and without the tune, you run some pretty substantial risks of damaging your bottom end.
Good luck. Hope this helps.
Bill.
__________________ 2005 Torch red, predator 93 octane, K&N filter, Pypes true duals, Eibach Pro-kit springs,4.10 posi 8.8 rear end. GT fanblades with Eagle F1's, GT500 rear bumper/spoiler/front splitter | 
