| | Re: has anyone went from 3.23 to 3.73 with a 3000 stall conv
What you've heard ("I've heard that tranny failure is unavoidable with TC change") is completely false. A mild low STR stall like a SY 3500 or a TCS 3300 with a 2.0 STR when used with a tranny cooler will not significantly increase your risk of failure. Sure, any mod (e.g. lid, catback, or TC) that increase power through the tranny increases the risk of failure due to the extra torque. However a mild converter is not that big a risk.
A 4000 stall with a 2.5 STR is different, IMO. That can really increase the max torque and the duration of high torque. Even still, bolt-on cars with very high stalls still have a pretty good track record of reliability.
Figure .2 and 2 mph from the switch assuming no TC. By the way, your rear is more likely to develop issues (e.g. whine or gear tooth failure) when you swap gears than your tranny is likely to fail from a mild converter swap.