Some more detail would help answer your question.

1. Which kit/plane are we talking about?
2. What's the overall weight?
3. What engine are you using?

In general, it sounds like a LOT of weight to me. Most planes are designed to come out close within a specified engine range. I know there are a lot of variables that affect this. I always strive for no dead weight, but if I have to add more than 1/2 lb (8 oz) or so to a 60 to 1.20 plane I start looking for better solutions.