LOL. I didn't honestly think you really wanted to do this. Anyway, just email a Lexus dealer (Carson Toyota, Park Place Lexus, Sewell Lexus, google any of these names and you will find their websites) and ask them what the largest dimensioned emblem is.
The point is, you don't drive a Lexus. You drive a Toyota.
Also, not all Lexus parts are made from "cheap Toyota parts." Many of the hoses, plugs, cables are made from different, stronger materials than in their Toyota counterparts. There is so much information to back my statement, on the web, on other forums, from certified Lexus techs. Anyways, it's your car, you do what you like. As long as you don't mind what other people think of you for doing such a thing, it shouldn't be a problem

Enjoy that gas mileage that you will get from your "Lexus"