I've done a lot of dyno testing of race engines with thermistors in the exhaust ports trying to evaluate the effectiveness of fuel distribution to individual cylinders. (Leaner mixtures burn hotter) The short answer is yes, porting and polishing affect fuel distribution and individual cylinder performance. However, unless a LOT of other factors are completely equal, I doubt if a measureable gain could be achieved on a street-suitable engine. We were shooting for an exhaust port temperature of 2,000 degrees F. on all cylinders under load at wide open throttle on Chevy 355 cubic inch round track engines at RPM's in the 7,000-8,500 range. Several of those engine were making 600+ HP, corrected for temperature and humidity. They also had a projected lifespan OF LESS THAN 1,000 MILES! Not your average street engine!
Jerry
