I have sold at least 100 of them and i have had 6 that had problems 2 with the distributors 3 boxes and 1 coil and i know for sure 1 was the customers fault because when he sent the kit back to me and i looked at it the wire's going into the box was melted the others i don't know i just replaced them for the customers.
I don't think there bad for the money .
Now there is another kit called a mega fire kit that is a killer kit put's out about 20% more spark than the MSD 6 al box . well that is what they say anyway i have sold so far 62 unit's and not one back and all of the local guy's that have them are very happy with them cost a little more but not a lot.
Hope this helps some.