Depends what you consider "Pressure" doesn't it mate.
One man's concept of extreme pressure maybe just a "Walk in the park cuddling fluffy puppies to another man.
It's all relative isn't it.
I'm not going to get into the whole going around sparring people of different systems thing , there is certainly merit in that , but most people have trouble enough making time to attend their own school let alone making time time to go to other peoples schools or spar outside of class time.
Most attacks whether they be hand / leg can be categorised as either circular (they will come around either side of your guard ) ie hook punch ,haymaker etc.
Or direct ( straight down your guard) ie jab , Wing Chun centreline punch.
They can also come in high or low ( above your guard or underneath it ).
There is also some overlap in this , a linear strike can also be aimed just off the centreline so it is on the outside of your guard aimed at your cheek bone or eye.
But without complicating it too much , they are basically circular or straight , high or low.
This is where we start to get into the territory of what we call in our lineage "Random Arms" and "Random Legs"
Eventually striving to be able to stop any random attack.
I assume Domino that you have "Four Corner Deflection in your lineage " that should be your first port of call.
Work on stopping circular punches to the head and gut like hooks and uppercuts.
Here are few things I wrote a while ago , they are drills and exercises to develop reflex.
They maybe of some use to you.
Fair bit of reading there mate , but you might find something in there you can use.
http://www.martialtalk.com/forum/showthread.php?67018-Four-Corner-Deflection&highlight=
http://www.martialtalk.com/forum/showthread.php?90528-Chi-Sau-vs-The-Flurry&highlight=
http://www.martialtalk.com/forum/showthread.php?89648-Reflecting-The-Elbow&highlight=
http://www.martialtalk.com/forum/showthread.php?68775-Reflex-exercise&highlight=
http://www.martialtalk.com/forum/showthread.php?79279-Bong-to-Tan-vs-High-Low-Strike&highlight=
http://www.martialtalk.com/forum/sh...i-pad-to-test-structure-and-stance&highlight=
The important thing to remember is that you start with these drills and ramp up the intensity , they are a stepping stone so that you have the attributes to handle random attack.
But at the end of the day they are only exercises and at some point you must accept that training at close range and realistic speed you will be hit .
It is imperative that you include the random stuff in your training , because this is where you learn to improvise on the "Fly" so to speak.
Such as you think he's going to throw (A) but he throws (B) so in turn you have to convert your original defence to something else in order to not be hit.
The defensive patterned sequences are great for developing a variety of things , but some things can only be developed by going "Random" with the threat of being hit .
Also it's worth remembering that whilst padding up with head gear , mouth guards , gloves , doing rbsd scenarios etc can certainly up the adrenaline level , it is not exactly the same as that horrible feeling of fear and dread that seems to hit you in the pit of the stomach when you've got two big blokes standing in front of you intending to do you harm and you realise you may have to do it for real , they certainly help.
But that feeling is really something you can only deal with the best you can.