No, taking the airbox out is not ok if you don't have a filter element to put in it's place. You really shouldn't mess with the intake on your car unless you are going to do some sort of fuel management with it. If you just want a little bit more flow get a K&N drop in filter though it won't really do anything except be reusable.

 

Also, if I do not get a cat back system, can I just connect the S+S Headers and Tanabe exhaust directly to the stock y bent Lexus exhaust pipes?

 

You COULD do that but then you are defeating the purpose of your headers. Your exhaust will only flow as much as the smallest/most restrictive part of the exhaust. If you install headers and leave the restrictive cat back on you really aren't going to make much if any power. If you want something thats going to be quiet with your headers try looking into the Borla exhaust (even though it's just a rear section) or to get the best of performance and low sound, try a Tanabe Touring Medallion.

 

That's odd, I remember a post where someone here did a before and after dyno with just the addition of the S&S headers and got 17whp. He did NOT have a full catback exhaust either.

 

The way that I am understanding it, I can use the Tanabe Touring set up for the back end but then, won't I need some exhaust piping to connect the Tanabe back end to the S+S headers?

Thanks for all the input really beneficial.

 

Also, does anyone know how much Lexus charges for their O2 sensor wiring harness? I was going to get the longer wiring set up to eliminate having to mod together a longer wiring harness, I want to make this look as clean as possible under the hood.