Matey turned up at the door just last week, demanding a pipe for his 150SP, so we sent him down the beach and threw one on.
He was paranoid and also demanded a handful of jets too, which I gave him to test with.
He turned up again the next day with a fistful of spark plugs asking my opinion. He had ranged from 152 (std) up to 162. The 152 looked luvely but we settled on the 155 'cos he reckoned he liked to hold it flat chat up to Bangkok from time to time and I didn't really want him back again with a seized piston in his palm.
He came round the next day to return the jets and was over the moon with performance.
I'd then gave it a try and ended up just tickling the RC valve setting a fraction and all I've had since was a phone call to say how quick it is. Job done.