A vehicle that has been modified so that it produces a loud, rumbling, aggressive noise when the engine is revved. This modification is known as installing a ‘Grunt Valve’
Dave: Bruv, what was that car that just sped past us, sounded like a TVR or something..?
Joe: Nah mate, saxo.
Dave: Shit man, must have a fat grunt valve innit.
Dave: What you sayin Joe?
Joe Just chillin in the grunt valve innit.
Dave: Fair play, whats the grunt valve sayin?
Grunt Valve: GGRRRRRRR – WAAAAP WAAAAPP WAAAAAAAAAAAAP!
Dave: That’s some serious grunt valve right there Joe, he is on it.
Joe: Innit doe.
Joe: Nah mate, saxo.
Dave: Shit man, must have a fat grunt valve innit.
Dave: What you sayin Joe?
Joe Just chillin in the grunt valve innit.
Dave: Fair play, whats the grunt valve sayin?
Grunt Valve: GGRRRRRRR – WAAAAP WAAAAPP WAAAAAAAAAAAAP!
Dave: That’s some serious grunt valve right there Joe, he is on it.
Joe: Innit doe.
by Badmaninnitdoe October 04, 2010