I have discovered i have a hole in my exhaust, a big one, here:

 

 

As in that above photo, but without the plug, its on the passenger side.

 

You can see in this pic what SHOULD go here:

 

 

How would this affect my engine?

You'd get poor airflow through the exhaust. The parts arrowed are the connectors for the AIV valves. Where exactly is it leaking from? Have you deleted the AIV system?

I think its for the EGR. Im pretty sure its fine to remove, this is done in the quest for reducing weight. Im sure the others will have more info.

Yeah removal of the iav system is fine, i never removed it, might have been like this when i bought it, or it could have been removed when the engine was rebuilt.

 

Si, see the first pic, imagine that WITHOUT the plug and the shaft, see the shape of the heat shield? well there is a big hole the shape of the heat shield, were the iav pipe should be (or egr pipe, not sure which).

 

Its really blowing pretty bad, amazing it passed its mot, how would this hole affect the engine running? Its blowing more from the drivers side pipe and less on the passenger side. I was hoping it was this hole causing the difference.

So the small adaptor is not welded onto that mid-section then?

 

I'd get a replacement mid-section if that's so badly damaged, the adaptor is missing. All you need to do then is plug that hole and the other and completely remove your AIV system.

 

Where's the pipework that should go to that? I guess it's still plumbed into the other one?

 

Holes in exhausts past turbos, won't effect cars all that much, it's NA cars where that comes into play. A hole that big would cause so much back pressure to be lost that it wouldn't run too well.

 

You may have issues with turbo spool and stalling? No entirely sure how it effects back pressure and scavenging properties on turbo cars.

 

You'd be creating a lot of turbulence there and may result in backfiring any unburnt fuel in the exhaust system which could in-turn destroy your cats (if you still have them).

 

The hole is after the oxygene sensors, so wouldn't effect running in that way.

Cheers Si, im not even sure of the drivers side one is connected, its of the axle stands now so i cant even poke my head under to check.

 

Anyone else got any input?