Got a race coming up...need some help from the pro's

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We'll this is the deal. A friend wants to run my wife's A4 wagon against his 240 coupe with a SR swap,GT35,huge intercooler/charge pipe,standalone, and on and on.

The Wagon is running pretty good with Bob's 2L stroker and the GT30, but only running it at 22lbs. I want to bring it up to 28lbs but need to know something. I will be running Tulene in the 93 plus I'll put some 101 unleaded in the tank.
How do I know it's cool to run that high of boost? I will be able to smell the fuel, but just don't want to get knock at that high of boost.

Wideband is saying 11.7 at 22lbs. WOT.

Alot is on the line and want to bring my "A" game.

Thanks
Mike