Who Still makes Yamaha RD400 expansion chambers? Is DG still around?\nWhat would be the best expansion chambers to replace stock pipes with\nno mods to the motor, carbs, airbox? The original pipes are damaged and\nwould like to replace with expansion chambers and hopefully not have to\nre-jet or add K&N air filters. Any shops or website stores that\nspecialize in Yamaha RD400 parts and exhausts? If I had to re-jet with\nK&N filters what size would you recommend with suggest pipe? Right now\nmotor is completely stock. I'm not looking for used original pipes,\njust want to replace with something that looks sporty. This is just for\nthe street, not racing.