The shift kit will get rid of/prevent code P1811, which is caused by other part(s) failing in the tranny. The shift kit is a "band-aid" fix that has proven itself for many. Many have done it, and some have thousands of miles and years of use on their cars. Well worth it for the price IMO. I have 4 years of use on mine.
Here is my write-up and info: http://chrisb.users.superford.org/Gr...Shift_Kit.html