Yes, the popping is a good thing!

My scorpion can causes a lot of popping when rolling off the throttle and on down shifts, but I like it that way, it sounds great!

Yeah my viper does the same, sounds lovely especially when in a valleyish area so it echoes :D

So popping is ok then? well thats fine with me. Dont think there are any leaks, work collegue (also bike mechanic) had brief look and couldn't find a leak. So if I decide to add a filter is it worth it? Would I get away with just fitting it as is?

Yeah, you'll get away with it... I have! When I changed my plugs a few weeks ago, it did suggest that the bike was running a bit rich (as does the mileage I'm getting now), but that's generally not too much of a problem.

The filter will ease up the running of the bike a bit, and you'll notice the difference at the top-end as well. However, if you've got both the filter and can fitted, the remap is something you should look to get sorted out.