You fellas that have to replace with new sludge plugs for your sludge traps, make sure and get what you took out. The newer ones can be thinner, and have a larger allen head fitting, which reduces the weight of the plugs, and of the crank shaft and affects where the balance factor is. So theroetically you could have a lower speed vibration, or a higher speed vibration. If you liked the balance factor of what you had before removing the sludge trap plugs, get the same weighted ones again, or possibly have to re-balance the crank.. This is what an old time Brit bike mechanic told me, so just be aware that it can have an effect. Some of the new replacement ones are much thinner in depth, and some have a huge allen head fitment on the top, which reduces the plugs weight, and changes the balance factors. Musky would know much more about this than I would, because he had to do balancing for the race motors. What say you Musky, please add to this, I am pretty sure I have some in-acuracies here , because it was 2nd hand info, and hearsay .