One could say that this project started a couple years ago when I bought my C5 to a local shop for some upgrades, including a 4" air intake, 4" throttle body (Nick Williams 102), and a 4" intake manifold. Imagine my disappointment when the tuner at this shop warned me up front that he'd only been able to get the NW102 throttle body to work on about 1 0% of the C5s he'd tried them on. And imagine my further disappointment when my car turned not NOT to be one of the lucky ten percent.

If I remember correctly, the throttle would idle reasonable well, but would only open about 15% before the car went into "reduced engine power" mode. But it's been a couple years so I could be wrong. There were OBD2 fault codes as well, but I have no idea where I wrote those down.

We ended up using an LS2 throttle body instead, and the car still made good power (475whp on one dyno, 450whp on another), and it was a ton of fun on my local road course (The Ridge, in Shelton WA), so I didn't lose a lot of sleep over it. 

But I did go home with a barely-used 102mm throttle body still in a box.

Part of the problem is that the C5 uses two separate computers to control the engine and throttle body. The engine is controlled by a Powertrain Control Module (PCM) that is also used in cable-throttle cars and trucks of the same era, for which a variety of tuning tools are available. The throttle body is controlled by a Throttle Actuator Controller (TAC), which nobody has figured out how to tune. The TAC probably needs to be tuned to match the NW102, but since there are no tools for that, C5 owners are kinda stuck. 

In the next-generation Corvettes, the TAC functionality was built into the next-generation PCM, and I suspect that's what makes it possible to integrate aftermarket throttle bodies.

When you ask about C5 / NW102 compatibility on the internet, most of the responses are "hire a better tuner lol" from people who have no idea what the solution is. Actual tuners either tell you it's not a solvable problem, or tell you that sometimes it works and sometimes it doesn't. After 20 years, there are no tuning secrets left.

You'd think that after all these years, the fine folks at the Nick Williams company would have figured out - and publicly documented - exactly what prevents these things from working consistently in C5s, and how to solve the problem. After all, they would sell even more of their throttle bodies! But it's not hard to find stories from people who work with Nick Williams to resolve this sort of problem, and ended up getting nowhere. Apparently there was a period when you could send in a factory C5 throttle body and NW would transplant the electronics in one of theirs, but that time seems to have passed. I can't even get a phone call returned.

So I vowed to dig into this myself. It's taken a couple years, but I'm finally starting on this path.