[Bob Gullett]

As per NHRA in the latest rules update.
SECTION 20: GENERAL REGULATIONS, ENGINE: 1, 1:3 EXHAUST (Page 3) (2/18/2014) All cars vehicles must be equipped with exhaust collectors, headers, or stacks installed to direct exhaust out of car vehicle body to rear of car, away from driver and fuel tank. No part of the exhaust system may be routed through the driver’s compartment. Exhaust collectors/stacks system components must be securely fastened (i.e., metal connector straps, bolted, welded, etc.) to prevent loss of collector/stacks system components during competition. Effective Jan. 1, 2014, All removable multi-piece exhaust collectors/stacks must be securely fastened with either an NHRA-accepted header tether, or a minimum ½” (half-inch) stitch weld located on each primary tube or be permanently attached to the vehicle body or frame with positive fasteners (i.e. exhaust hangers, support brackets, bolts/nuts, etc.) such that they require tools for removal to prevent loss of collector/stacks during competition. A current list of NHRA-accepted header tethers is available on NHRARacer.com.