[Azathoth]

Everyone in Edmonton area has gone R-Hop / ER hop. It's a night and day difference when compared to stock guns.

My opinion in shooting distance and accuracy worst to best,

Stock
Stock + SCS
Stock chamber + upgraded rubber + SCS
Stock Chamber + upgraded Rubber + SCS + Upgraded Bore
Upgrade Chamber, Upgraded Bore, upgraded Rubber, SCS
same as above line with barrel shimmed + ear plug mod variants.
PTW hopup - STOCK
Upgraded Chamber, Bore, Rubber, R HOP
Upgraded Chamber, Bore, Rubber, R HOP w/ M nub mod
PTW Tackleberry Mod done properly
Upgraded Chamber, Bore, Rubber, ER HOP w/ EM nub mod


EDIT:
depending on the hopup chamber in your gun that may actually be a far better upgrade. Typically a SCS + Rubber upgrade is the cheapest and best bang for buck upgrade. Costs ~10-15 dollars.

EDIT 2:
The PTW mod done properly IMO is just above R hop + M nub + barrel shim + ear plug mod variants. This comes down to the technical skill and time spent doing said work. PTW hopup and components interface in such a way that they don't require barrel shimming or the earplug mod (technically ensuring the buffer cap is shimmed properly -is- the same as the earplug mod.