Just popping in to say hi from overseas.

Just got my stock standard white ZX-6R like 3 weeks ago, has 500km on it now.
Just wondering if anyone can help me with this issue....
after 1st oil change, I took it back at 250km, I started to hear popping from exhaust after I get off the throttle.
haven't changed the type of petrol I use (regular 98oct), I haven't even changed the petrol station I take fuel from.
Its always pops when I get off the throttle and shifting down, constant boom boom boom, but once I crack throttle on, its disappears, accelerating is fine and smooth.
any ideas? change petrol station? change to superior 98 oct fuel? would they have messed with the fuel management system on 1st service?
I will ask them today, but its 930am over here and I've been thinking about my bike for...........gezz.....everyday since I got it.....I AM ADDICTED

I'll try link a pic later
THANKS GUYS