As en ex novice racer in the 600 supersport class & someone that had to hands on strip down an rebuild the cans on my bikes to adjust the noise for noise testing regulations, a race pipe, is not very restrictive, they baffle sound by means of a highly perforated tube that is wrapped in exhaust wadding, the tighter the wrap the louder the it will be an vice versa i would advise getting a lightly larger bore, as making up 5mm or 2.5 either side of the flanges will be diffcult. on a bike the length of the rear box will adjust the power delivery, a longer can will allow the power to come in further up the range, a short can will give it to you in a fat short band all at once lower down he revs..... not quite sure how this is going to affect your golf.... i would imagine it will do nothing performance wise at all
after all TVR's use bike cans, my mate at Blueflame exhuasts makes them for some users.......
