Haven't met a PCP that couldn't be:1. Modded up for more power (but less shots).2. Moidded down in power (but for more shots).3. fiddled around with in all sorts of ways, for more efficient air use.Don't think the Gamo Urban is immune for this.So if you are bored, pick one of the three and go from there.
But in order to NOT keep working until doomsday for fractional results, would be best to pick a goal BEFORE you start the project.
The actual barrel length of the Urban is only 15 inches once you remove the whisper.