[elhigh]

The vacuum gauge works even if your OBDII systems are wonky. I have one and its calibration is way off, but movement of the needle is sufficient to give you a moment-to-moment read on if you're asking more or less of the engine.

Being a 97, your Corolla should be fully compliant. Torque app on your phone and a bluetooth connector gives you nearly the same kind of monitoring as a Scangauge but for way less money.

For my part I would prefer a Scangauge, if only because it means I don't have to lay my phone on the instrument panel. But that's me.

There's some debate on wheel skirts. Not much around here, the hardest core guys have them, including a couple of Metros and Civics that are pulling down sky-high numbers. And of course, what works on one car may not on another. I lean in their favor. If you can equip some better instrumentation, you can do some ABA testing to nail down whether skirts can really help. I think they can, but their signal may be too small against the noise of other things going on and you can't get a really precise read on your car since you can only calculate tanks.

Welcome, by the way! It's fun here. It's a different kind of performance driving.