Boost spikes!

I've recently had a boost gauge fitted to my GT, after having had a CBE on for a couple of months and a grimmspeed 3port boost solenoid put on at the same time as the gauges. The car also has a light tune from the previous owner.
What I've noticed is S# has a higher boost setting than S, but while boost level in S was smooth, hard accelerating in S# would give a horrendous spike to around 1.5 bar! before settling to around 1.0
That was scarey and I've barely used S# since, tho by easing up to boost and THEN mashing the throttle the boost level is fine.
I was just idly wondering which was more likely to cause that? the tune? the CBE installed without a retune (my guess)? or the boost solenoid?
I just avoid S# for now. I have a proper tune in the near future organised (after a dump and cat go on as well) so I'm hopefully! not going to pop the motor in the meantime. I'm just glad I have that boost gauge or I'd have been blasting around and spiking the motor on a regular basis completely oblivious until it blew up one day and me blaming the motor for being weak
What I've noticed is S# has a higher boost setting than S, but while boost level in S was smooth, hard accelerating in S# would give a horrendous spike to around 1.5 bar! before settling to around 1.0
That was scarey and I've barely used S# since, tho by easing up to boost and THEN mashing the throttle the boost level is fine.
I was just idly wondering which was more likely to cause that? the tune? the CBE installed without a retune (my guess)? or the boost solenoid?
I just avoid S# for now. I have a proper tune in the near future organised (after a dump and cat go on as well) so I'm hopefully! not going to pop the motor in the meantime. I'm just glad I have that boost gauge or I'd have been blasting around and spiking the motor on a regular basis completely oblivious until it blew up one day and me blaming the motor for being weak
