The pro kit is actually the exact same thing as the TRD springs from Toyota. I got mine delivered with my 86, new from the dealership and with full warranty. So even if they make the shocks operate "lower" with less damping distance, it doesn't seem to bother Toyota for premature wear.
I suppose your dampers have different specs than mine, but the Pro Kit gives a reasonnable drop without being too harsh (no more than the stock setup).
You might be able to keep those Sachs longer than you think.
