I replaced the factory single exhaust on my 85 EC with dual exhaust with dual catalysts when I bought my EC 8 years ago. The performance improvement was substantial including higher RPM range, faster acceleration, more low range power with a little improvement in gas mileage. The guy I bought my EC from sold it to me because he felt that my EC (with single exhaust when he owned) could hardly pull itself let alone his 4000 pound boat and trailer. Have others experienced the same increase in performance. Have others compared the performance with and without catalysts. If so, how much difference did the catalysts make.