tune...chip???

Chips work the same way your tweecer worked.

A modified tune is loaded to the chip/module.
The chip/module is then loaded to the J3 port.
Anything plugged into the J3 port over-rides the factory settings.

Save your money for now.
You can play with the AFPR and timing just as well as a dyno shop.
It may take you a couple more attempts before you have something you're happy with.

jason

AEM widebands are now 299.95 from summit

The LC-1 can be found for $199


Yes,
The local dyno can view what your afr is, that isn't the issue.

The problem is that changing the afr away from stoich for more power, will have no affect in the long run.
The car may make impressive dyno numbers, but after it is driven for a while the ecu will start pushing the afr back toward stoich.

The Adaptive Strategy will work against tuning with fuel pressure.

It is best just to set the AFPR to stockish, and make small adjustments from there.
You don't have to tune the afr dead on using fuel pressure. You just have to get within the range of the Adaptive Strategies ability to correct.
Obviously, you don't need a dyno to fine tune the ignition advance...

Save the $ for something that will have a lasting benefit.

But, that's just my opinion...
jason