suggestions for intercom/headsets for high noise environment

Hey guys, think I have narrowed down my decision to buy a sigtronics SPO42N portable intercom to be used in an open cockpit. I will be dusting off my David Clark 13.4 headset to use but would like any suggestions for a decent but not too expensive set of headsets for my "passengers". It would be nice to keep the price below $300 since I will need to buy two more headsets, but if anyone can suggest a good headset for a high noise environment, or a better intercom, please let me know. One of the nice things with the Sigtronics intercom is the 4 foot chord for the passenger headsets, that will be a must for any intercom suggested. Thanks.