losing power from rebuilding?

[Just another 240]

When someone do a bad job on rebuilding a engine, would the engine lose power?

Because my 240 runs smooth and good i can say, but it just the lack of power when i pop my clutch while i'm changing from gear to gear. I think my engine was rebuild and i can see they did an pretty bad job with the outside because I see that they only used rtv sealers instead of gaskets and i don't know how good or bad of a job they did in the inside. 2 of my other friend owns a 240 and when i test drive their car i can feel they have more power in their car than mine.

[Infinitiguy19]

So many things it could be but start with a compression or leak down test.