I have a custom exhaust system on an 85.5S with auto tranny. No cat or air pump/one muffler with twin pipes to rear was the original setup. The car is chipped and everything from 3,000 up was improved, at upper end improvement was really noticeable. At local PCA Race Track Driver's Ed Events could stay with last model GT on straights. But noise and low end was a problem on street. Experimented until I put two Super Trapps on the end. Add plates for street and get back all the low end torque. remove for track. Great performance flexibility plus they look really great.
928 Tips Home Greg's Home