you should hear a slight tick at normal revs if it is there you would know also if you put ur hand over the exhaust and block the exhaust fully and if the engine stalls , NO Leak if it continues to run mmmmmm big leak, also you can tell by checking ur boost gauge if it reads below 7psi at full power you've got a big leak, if so expect to pay about $600 fitted get 2nd hand manifold don't pay more than $180 good luck