I have a S510 also and my guess is your reading about people in the UK not wanting to hassle with modifications is on the non-FAC guns. Those guns have anti-tamper implements to keep them from being modified per UK law. If I remember correctly you can't access any of the valving without nearly destroying the gun. Even when it comes to rebuilds, people recommend sending it back to AA or an authorized repair facility. The FAC guns are totally different and easily repaired. I also read that on the FAC guns, the biggest mod people tried to add was a regulator and they found it had no marked advantage especially when you consider the cost. Never heard of anyone adding an anti bounce mod because from what I read, it wasn't needed. I did a bunch of modification research when I got my S510 and it appears that AA designed and built the guns right and modifications weren't needed. You also don't here much on tuning Daystate or FX airguns. I guess you get what you pay for.