I replaced all of the foil type ducting in my Alpenlite 27sl with full 4 inch dryer vent ducting , 4 inch aluminim ducting and sheetmetal KD elbows. Paying close attention to clean bends and sweeps. My outlet temp before was 125f and 170f after.
2001 dodge 2500 auto, with billet Mojave Green torque converter with 2nd gear lockup mod, raptor 100 fuel transfer pump and gauges. RV275 injectors
94 Alpenlite 27sl with many mods. Master mechanic over 55 years