Throttle Thump

[theoneillusion]

2008 S4RS. A few days back I blipped the throttle and was suprised to hear a thump sound, similar to launching a bottlerocket out of a tube. I thought it was odd but carried out. Today the same thing happened. Stopped and blipped the throttle with the first resulting sound being the thump sound. Any ideas?

[stopintime]

Vacum somewhere? Airbox, filter, throttle bodies, intake manifolds, tank ...

Obstruction? Crank case breather, shooting rats out of the exhaust ...

No experience, just trying to think here 

[Speeddog]

Makes a "Kuunk" sound from the airbox?

Generally indicative of lean fueling or due for valve clearance adjust.

[theoneillusion]

Ruh roh, you may just be right about the valve clearance. I know I'm due for it, just was waiting for winter to roll around.