If you fitted foam pod filters without rejetting, there is a good possibility it was running lean, and therefore very hot at MAX RPM/load, and giving it a good spanking could indeed [and often does] leave the packing in the silencers smouldering a little! If it's set up well, I always consider it a sign of a good blast!
Best results with an airbox we've had has been with 4x 20mm holes in the front slope of the lid, with the standard foam filter, and jetted to suit. (You can apply duct tape over two of the holes in very cold conditions to richen it up just a tad if necessary, to save a temporary re-jet.)
The OEM R5/6K expansion chambers are actually very hard to better, although they are very heavy and of course don't make peak as high as a set of "race" pipes. They trounce the mid-range of even the best race expansion chambers though, which makes them much nicer on a road bike!
_________________
Andy.
NSR-WORLD.COM
Please keep all responses to Forum posts on the Forum so that others may benefit.
Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.
Check us out on Facebook! Please "like" our page!