can someone tell me why i cant gain enough boost when i rev to hear my bov but i can when im driving?

can someone tell me why i cant gain enough boost when i rev to hear my bov but i can when im driving?
Your engine needs to have load on it to build boost.

you build boost reletive to load on the engine.

if in first gear you may hit max boost at like 5k

then in second you may hit it at 4600

third 4300

fourth 4100

fifth 4k

thats all just an example because your engine is fighting against gearing

but in neutral you have no load on the engine from from your gearbox because you are not turning any gears

ok i see but how can sone cars do it? i was at a car show last weekend and a rx7 was blowing off on a rev.