60k on my ConFE with no trouble. daily i drive with 350hp and i've dyno'd up to 435/1006. i on't baby the truck, but i don't drag race or pull either. 10k-13k trailers for probably 15k miles doing all of the mountain passes around Cali. Grapevine to LA (and Mexico), Hwy80 Donner Pass to Nevada, Siskiyou Mountains to Oregon and never an issue.
No personal experience with Valair, so I won't compare, but I LOVE my Southbend and the customer service when I bought it was SUPERB.
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2001 QC LB 4x4 HO 3.54, boost/pyro gauges, B1-2-EX4, F1 Mach3, Smarty, Blue Chip FMS, ConFE, DSS, 4.5" lift, 37" Toyo M/T, Airlift airbags, Thuren track bar and crossover steering