nicky7,
turn left at the traffic light after summit is on ur left. then at the next traffic light turn right, go all the way straight past the next traffic light, after that you'll see a big whitish building to ur left, turn left there and keep on going straight till you pass a halfcut garage on ur right, then turn right then left. immedietly you'll notice a signboard to your left (AH Exhaust Works or somethihng like that) that's Ah Heng's shop.
real good workmanship...nuff said. and i agree with joker with the price vs quality statement. my local straight flow muffler produces a slight humming noise after 4000rpm, prolly resonance with the fibres inside the muffler...but oh well. :D