I'm running two Dakota Digital speed signal converters for my J35/6 speed manual swap. Converts the ATC6 speed sensor signal to something the J30A1/J35A1 ECU can use. From there you can also dial in the accuracy and correct for any tire size induced errors- or in my case, error from the manual transmission! Here's a clip of my wheels:
I find that the TL wheels & tires offer a great deal more stability; but the front end will get kind of squirrelly on me if I don't have a good front alignment, worse than with the stock wheel & tire size. But, when properly aligned, and with these fantastic Toyo tires, the car is VERY manageable at all speeds and turning angles! If you do nothing else, get some TL wheels from the junkyard and put GOOD tires on them... you shant be disappointed!