Pump will make the price rise, dump will make it fall. I believe. 
See it as a supply and demand thing. If you dump you will increase supply thus lowering price.
See it as a supply and demand thing. If you dump you will increase supply thus lowering price.
Thats right, pumping and dumping takes a lot of resources however to really move the price on gox. The idea is to knock out peoples limit orders to buy or sell and profit on the manipulation caused.