Performed a heater tune-up on a Trane gas furnace system. Checked the electrical, mechanical and performance systems of the unit. Cleared, cleaned, flushed and treated the drain line and cleaned the exterior of the furnace. I replaced the high voltage wire nuts with a Wago wire connector. I did find that the gas outlet pressure at the furnace is high at 9.1in. w.c.. I lowered it to the rated 3.5in. w.c.. I also found the system has high static pressure but due to the location of the system there is no space for ducting improvements. No other major issues were found, and the system is operational at this time