I have a STS D5 and it is a very good engin so far ive only had it for about a week now and it runs good. Very fast
But i dont know much about that sts engine lots of people say they have lots of problems with the con rod.
they after run you should change the rod and the engine will last you lots longer. So if i was you i would change it after run in.
Thats what i did with my D5 anyway.
Hope this helps.