1974 NASCAR International Stock Car Racing Rule Book Modified Division Section 20C-9 -- Exhaust

a. Muffler must be removed. Exhaust manifold optional.

b. Exhaust pipes must extend past driver and to the outer edge of the car.

c. Exhaust pipes may be beneath race car or come out aft engine at cowl and mount on approved nerfing[sic] bars.

d. Extra mounting brackets are mandatory.

e. The chief inspector reserves right to reject improperly mounted or unsafe exhaust pipes.