I asked the same question on this forum for my HZ 253 and ended up with extractors, twin 2 inch stainless pipes, no balancer and Lucky Glass mufflers. Sounds mean at low revs and gets loud after 3000 RPM. It does get too loud to hear the sterio after 90 kph (only 1100w amplifier) but I think that all vans do drum at speed? I just drive slower to enjoy the noise.