If it is tight it will stretch and wear very quickly, put undue load on wheel bearings and swingarm bearings, in the worst cases the chain brakes and puts a hole in the crankcases or wears out gearbox bearings and shafts. If in doubt give it more free play not less. Carbon fibre mufflers out-perform alloy or steel mufflers . The answer of course is fiction. The only reason for the use of carbon on mufflers is to reduce weight.
Carbon fibre is used in many areas on race bikes, purely for it's strength and light weight.
Well, thank God for tubeless tyres. Not only did it not deflate in one miliisecond going through that 150 km plus sweeper last night, but it can be repaired cheaply and safely. There are special plugs available to repair the new generation of tyres as long as the puncture is a clean hole and not a big gaping slash. Another thing to be aware of with radial tubeless tyres is that the PSI rating is normally much higher, eg 36 psi in the front and 40 psi in the rear is a fairly common rating. Spark Plugs I'm sure that many of you at some stage have been given the sales pitch on the horse power advantages of fitting brand X spark plugs.