E-tubes either richen the mix or lean it.
With 140 mains and F-11 tubes at 4k, 4.5k, 5k, and 5.5k rpm my EGT's are cooler than at lower than 4k when not fully dominated by the mains. EGT's don't increase at all at increasing rpms over 4k. The runs are in 5th gear for 10-30 miles flat throttle in Nevada. Idles are 60 @2.5 turns.
Have not same run tested 135 mains and 55 @ 2.5 turns yet but I presently can only assume same results with just the expected and wanted 25F EGT increase.
disclaimer: this is for a street engine
if interested in my EGT CHT JPI-700 aircraft engine monitor vid
http://www.avweb.com/marketplace/products/jpi-edm700.html