Compressor surge

After upping the boost to 1.6 bar on the dyno I seem to be getting a touch of surge at WOT and partial throttle around 5-6k onwards, dropping the boost to 1.5bar cures it at WOT but not at partial.  I know of others running a 3071 at 1.85bar and not having surge issues so curious as to why I am?

I thought perhaps too small intercooler piping but I'm pretty sure it's 60mm at it's smallest parts in the run so shouldn't be an issue, what else might cause a bit of surge? It's not a massive issue as I'm looking to go full 3" on the exhaust and run less boost but would like to know why.

Read More at : http://www.gtiroc.com/forums/technical-questions-/88509-compressor-surge.html

This video shows what I'm talking about despite the title, https://www.youtube.com/watch?feature=player_detailpage&v=_K0LFadOKBc#t=51

Thanks.

Dose this not tie in with your large compressor to small turbine which will give give better low rpm enhance but will cause surge top end high boost

I've really no idea, has been suggested to map the boost with my EBC as it has an rpm map function and reduce the gain when surge starts.