BlackBubble

I installed the VAIS on my '05 GX and it's not that difficult, from 0 to 10 (hardest) I would rate it a 5. It took about 30-45 minutes. I put the VAIS unit under the glove box panel so it can be easily remove or change the mode. Good luck with the mod.

Some cars require it while others are just recommended. The VVT-i engine GX's (05 and newer) all require premium while it was only recommended (hence 87 may be used) for the 03-04.

That's not true according to my 2005 Lexus GX470 Owner's Manual under Fuel Selection section, 91 Octane gas is NOT REQUIRED, but "Recommended for improve performance"

" Fuel selection:

Select Octane Rating 87 or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 or higher is recommended."

I've been using 87, 89, and 91 Octane gas and have not noticed any difference in MPG.

The Lexus battery is guarantee for 7 years? I never knew that.

What does that mean to me then?

I believe you will get some credit toward the purchase of a replacement battery (same brand, retail price).

Does the K&N air filter affect gas mileage at all?