Spearco Electronics used to make a very inexpensive unilt for under $125.00
I've used it before with success but only notice a small gain in acceleration and boost but the primary reason for the purchase was to get rid of the pinging which it did under heavy acceleration. But I don't see them in aftermarket use anymore. I bet E-Bay may have some. Thinking about finding another unit and adding it to my car in order to advance the timing a bit more and get a little more gain out of the engine
