Yes... I making stock vehicle. And some problem happend. I made first stage to LDO SSTO and perpect engine. But when Attached it to second stage, First stage'DV is be down under 2000. And second stage have lower DV than real thing same weight, size.
I think it is game's problem and fixed my rocket's weight. But weight fixing is not good think. It make fuel weight too.
How to make stock rocket?
Your grammar is rough, but i will try to help.
The delta-v of the entire craft has to take into account the weight. The engine may have a large amount of delta-v, however, the weight of the rest of the craft will lower this. This also means that the designer readout can be inaccurate, since as more fuel is used, the weight is reduced, which increases delta v of other full stages. The upper stage's delta-v will increase as the first stage's fuel is depleted. So, it is not a problem, and you should be fine.
@Staticalliam7 Ok i see. Hmm... I will check it.