4L60e question on hp rating
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I'd get the 70274, but if you want to save a few bucks the 70266 will be just fine too.
120k on mine with countless track passes and daily driving.
If either shift kit is installed, I would highly recommend also installing the Sonnax HD 2-3 shift valve. The trans is then stronger when raced in D3. (The overrun clutches will then share the load with the forward sprag in 1st, 2nd and 3rd gear.)
Some benefits of the shift kits can be realized by just installing a bigger boost valve such as the Sonnax 4L60E-LB1. (-LB2 for '06 and later) This only requires dropping the pan and filter and using snap ring pliers to replace the boost valve. This will increase line pressure across the board and increase the maximum line pressure at WOT. Less than $30. Shifts will be slightly firmer, but I suspect most people on this forum will be OK with that.
However as mentioned, a bigger cooler is the #1 improvement.
Last edited by mrvedit; Jul 1, 2013 at 10:26 PM.









