If it's a street engine, then it gets the same warranty as the others. Essentially the short and skinny of it is if it breaks because of something I did wrong, then I'll fix it. If it breaks because of something you did (or an installer did) or a parts manufacturer did wrong, then I'll help out the very best I can.
I provide 1 year limited warranties on my stuff.
Here's the long and fat of it if you're interested in reading:
Lykins Motorsports, LLC
I haven't ran into a lot of issues (knock on wood), but I think that those customers will attest that I do a good job of taking care of things.