Mail-in ECU Flashing

Hey all, I'm looking to get an ECU remap/ tune for my Gen 1 MT-07 after swapping out the exhaust, air filter and modifying the airbox. The changes are pretty common, nothing unique.

I've been calling around a few Dyno garages, but have been a bit shocked at the cost of a Dyno tune (£5-600+).

Mail-in ECU Flashing is therefore a tempting option...

I was wondering if anyone here has experience with mail-in tuning from places like P3 Tuning, Velox Racing or Wiz Performance. Would you recommend? How do they compare against a proper Dyno tune?

Would be great to hear your experiences/ knowledge.

All I'm looking for is ensuring the best air-fuel mix for my setup, ideally a slightly smoother throttle response with decreased engine braking and finding any little additional power that's available.

Cheers in advance!