V70 T5 How much is too much boost?

[960kg]

I am trying to understand this boost business!

In the 850 section there is a similar question but this i take it is with the 15g turbo?

I have the uprated engine in my `97 V70 the B5234T3 but with a 16t and HLM304map and i run on 20psi no probs. yet after 2yrs!

I have just purchased an 18T from a member on here smithson007 and am fitting this week so what would be a safe boost psi?

The bit i am trying to get my head around is the fact that the larger turbo the more air it will supply at certain revs so why doesn`t the psi have to be lowered when a bigger turbo
is fitted to be on the safe side.

As an example: if 15G up to 20psi is used and i use on a 16T 20psi surely it is more dodgy using the same psi on the larger turbo.......or am i seeing it the wrong way?

.....and then what happens with an 18T.........does the map sort anything out?

This 18T i have just bought has the straight wastegate and it came off the early V70R so what was different on that motor to keep the engine safe?