Lexus IS300 RMM Exhaust uses a stainless steel muffler, While cruising at low rpm's the exhaust is relatively quiet, but when the throttle is pushed to the floor, the car seems to come alive with a deep, race-car like tone! RMM's exhaust is now ready to ship! RMM uses a 4" angled, polished stainless steel tip. RMM's exhaust is not technically cat-back, as there was a resonator that would have to be removed. RMM felt the result would be an exhaust that was too loud and obtrusive.