I fitted Perry extractors to the manual 3.5 in 1986. There was a noticeable difference in performance we had a steep hill to go up leaving house which prior to extractors we had to be in second. After they went on it would go up in 3rd. Same on other hills. No other change made. Currently running ceramic coated headers they’re cooler than cast manifold back into y piece then single 21/4” to muffler and resonator.

