This sounds like i am running the wrong master cylinder. Googled a bit an a bigger bore size will give less pressure. However i don't understand why it would change the front-rear pressure?

Have checked what piston diameters i need to have to check that on saterday. Front needs to be 60mm for the 4x4 sierra/escosworth and rear 43mm for the cosworth 2wd or XR4x4.

Maybe i have an issue in my master cylinder, so will have a look if i can swap that one for another one.

I WILL GET IT FIXED FFS