Nothing would be 'piggy backed'. You would be using a stock chip essentially. OBD2 can process faster but I don't think anyones setup here is at the point where an OBD1 setup would hinder anything.
The stock system is well proven and VERY complex. There is a TON of things you can change to dial in your tune. You can see everything you can change on the TunerCAT site if you look at your definition file. I know I can even change the knock refresh rate with my pcm.. not positive you can in a 93.

Don't take this as a knock. I'm just trying to emphasize that a great tune could be had from using much of what you already have.

I've been to the TunerCat site a few times. Printed out the '93 definition file, and the '95 file....and much has changed between those years. So much so that the EEPROM doubled in capacity. While the 94/95 PCM is probably fast enough to do what I would like to do, the OBD 1.5 protocol is something that kills that option for me. The options you listed are known to work for the 94/95 pcm...unknown for earlier years. If I were to buy those options and try them, and not work....I'm out on money. Buying an OBD2 PCM, on the other hand, can be sold to someone else on the club much easier than the Ostrich setup, if this fails. Again, looking for wide availability, because if this project fails, I can offload my materials easier.

I know you weren't knockin. This IS P&B, this topic IS a brainstorming session. And I am not afraid to eff things up with this car. It isn't a daily driver...never was, and probably never will be...so I can afford to be more creative with it and run risk of failure. Or take my time and be successful.

EDIT - I saw you posted the Ostrich WILL work for the '93 chip. Still doesn't allow me to run an Aeroforce in the future though Oh...one other thing I would have to change on the motor...the EGR system.

I say go for it...stranger things have been tried. I have the 96 FSM you can borrow if you want...I won't be doing any work on the car for quite a while. I also have either a 96 or 97 harness that you're free to rip apart.

I would be very interested in trying this sometime next year. I am very interested in your findings as your research and progress comes along.

Did I mention that I have most of the firewall pinouts listed out in Excel for 95-99? We add 93 and then map them over... map over the wiring at the pcm and new additional needed wiring..you'd be off and running.

Personally though.. the quickest way would be to swap your engine harness and make an adapter like I suggested to Randman to interface with the items left in the passenger compartment at the firewall and have the pcm in the engine bay.

As much as I like that idea there Boosty, that effectively cuts off my escape route in case of PCM failure on the road. I would rather do it the way I suggested for the interim, until it is proven the OBD2 system CAN run the S1. When there is considerable runtime on the OBD2 setup, only then will I change out the harness to a more correct version.

Wow....lots of support on this idea

It would be awesome if we could tune the series 1 on the fly the same way as the OBD2 system cars.

If anyone is interested in doing this for the 1992 year. I have all the wiring diagrams for that year if anyone is interested.