Has anyone heard of real results on the S197's by putting one of those $95 dollar throttle body spacers on?  They claim 16 to 20 horses and a 4 mpg increase...sounds too easy.  

I wouldn't count on that big of an increase. I saw an episode on Horse Power TV, where they were talking bang for the buck. You may see a couple of horse power, 5-6 at best with a tad bit of improved MPG. I installed a Poweraid throttle body spacer, which was 52 mm. It was mated to the stock throttle body, and it gave a cool sound, and did seem to improve throttle response, and gas mileage, mildly, but I also had a K&N cold air kit. I swapped the stock TB for a BBK 62mm, and got the Steeda 62MM spacer. It is supposed to increase air flow and volume, but be careful, if you don't do a tune, or have tune done, it can actually decrease HP, because of the cars pc sensors, as they are very sensitive. I noticed a great difference in get up and go, and responsiveness, it got rubber in second alot better, with no effort really, but I installed a tune from my diablo predator programer. Hope this helps.  

I've never seen a throttle body spacer do jack on any car on our dyno. BUT most of the people who have them insist that the drivablity and response is better. One guy claimed to be a tenth and a half faster at the track.
I guess I'd have to see it to believe it.