Tumblers restrict air flow, these can really be upgraded at any point. Im planning on lifting the restriction on the intake track all at once. That is, extrude hone intake, tumbler deletes, and gasket match all the intake, tb, and tumbler orfices. I already have a FMIC, CAI, and ported Throttle body. All those things would get you about the most free flowing intake system possible. My tuner has preached to me alot on the amount of gains he sees from the gasket matching, tumbler deletes, and extrude honed intake. No matter what the rest of your parts are this will give you gains. Make sure you have the injectors to support it though.
Also, you dont need to buy the $500 APS tumblker deletes. You can find many shops around that can machine your tumblers for you for $ saving and you get the same thing. Id try Axis in st. Loius. sure they do it.