Dave,I reckon you may be seeing the start of engine wear and tear causing the heavy breathing.My car is only used on track and I've no problems with oil surge,pressure is always up in the corners,and theres no oil out the breather.Maybe you could try an uprated Bailey Oil breather??As for the sump,the std sump is very highly rated by Karl at NMS.When he built my engine I asked about a gated sump and he told me there was no need.Which I agree with from experience on track with mine.Here's a good link which you will find interesting reading

https://passionford.com/forum/showth...highlight=sump

All the best,Micky