higher boost pressure with exhaust???

[beez]

there are a quite few people reporting they are seeing higher boost pressures after changing with custom made or branded exhausts from downpipe to tail pipe.

could such a thing be justified?

one person with stock ecu reported seeing 0,7bar steady boost until it reached 0,8 where the car entered limp mode.

this is really weird, can anyone think if the above could hold?i.e. less restrictive exhaust higher boost?

[Garth]

Changing the exhaust should have NO affect on the boost pressure.

[max_torque]

I would expect to see small transient differences in boost pressure when a low back pressure exhaust is fitted. The reduced back pressure will increase the turbines efficiency, and also the reduced back pressure on the engine will increase the airflow through it. Both of these will cause the turbo to produce boost at a earlier lower rpm, and for longer at high rpm. The std contorl system will be expecting the response of a std exhaust so it is likely thaat you will get short periods of time where the boost spikes above the set point. However there should still be enough "headroom" in the control system to maintain the target boost under steady states, ie WOT accel through say 3rd gear.