I drilled and pulled out the restrictor end caps off a set of Stock Speed Triple pipes that's now on my Sprint. On de-accel., I notice it has a popping, could mean a little fuel screw tweak, or something that occurs when the 'system' is simply upset. The increase in 'Tone' is minimal really, at idle there is a bit more rumble and on blipping too. As to when you ride I would say a slight performance drop, ever so slight - the roll on is a little less, wooly perhaps. It's all very metaphysical I know but there is always a doubt and chances are it's not a reversible route taking the end caps off. It might be simpler to pick up a couple of matched cans from a Scrap yard and make them fit. Just my 10 cents worth.
