I have done the TPS thing. My idle voltage was 0.61V. I increased it to about 0.66-0.67V.
No matter how rich you will make the system, there will always be
some backfiring (Especially on the aftermarket mufflers). With the adjusted TPS setting, I still get some backfiring, not a lot though. If you roll of the throttle suddenly after accelerating a bit, it will tend to pop no matter how rich it is running. (Atleast 1 out of 3 times, and this is deliberately trying to make it backfire)
I've read on our forum before, probably through ScooterBob or Scotty the Ducaty, that the torpedo also backfires but it is more subdued. I have got used to it now, it happens rarely and when it does happen it's like