Engine Noise

Any ideas on this noise?? Sounds like it's blowing out somewhere but it is also backfiring in to the inlet manifold. I was doing about 4500 revs on full boost when it started to miss, got home and it sounded like something serious. Haven't had time to take it apart yet so it might be an easy fix but I don't like the sound and the backfire...

https://youtu.be/PA3Izh_xBX8

Hope the link works - my first attempt at Utube.

Link works fine john ..... its hard to tell from the video .... it just sounds muffled with a tinge of rubby belt noise if you think it sounds like its coming from the inlet side and its back firing could be a blowing gasket ?

Yes, my first thought was belts or bearings but it's definitely from the inlet manifold but if it was the inlet manifold leaking then I'm not sure why i'd get the backfire. I'll check compression again tonight, they were all at 150psi on Saturday - but that was before it went wrong.

Sounds like plenium gasket or inlet gasket to me

Sounds like inlet gasket and wouldn't you get a back fire because its letting in air so its not a sealed civacum circuit anymore

Well looks like I panicked too early. Took the intercooler off and 2 of the little rubber blanking bits had come off!!
Can't believe what a difference that makes... Are those connections ever used for anything or can I just stick a blob of solder over the top?

Thanks for your suggestions.

yh they blow off, just weld them up. iirc they were to individually balance each throttle body..
http://www.gtiroc.com/forums/showthread.php?62576-Permanent-cure-for-throttle-body-rubber-caps-blowing-off&highlight=blob+weld

just blank them off john or weld them up