If it's not really about tuning or wiring. Then it belongs in here.
i have tuned a race car that is built to handle up to 3 bar boost, the car made 1090whp on 2.2 bar boost running on E98 fuel, but i am facing a problem that as i go higher on boost the hp doesn't increase anymore, what could be the stopping factor? The turbo thats fitting on the car is a brogwarner that is sized similar to the garret gtx45
So many things.
Maybe the compressor is at the choke line (maxed out). Maybe there is too much backpressure due to exhaust system restriction such as downpipe. Maybe there is too much turbine inlet pressure due to turbine housing size A/R being too small. Maybe you have valve float. Maybe the intake to the turbo is too restrictive.
Or just to less ignition timing on higher boost.
Does the engine have the same ignition timing if you go up with boost?
There are a wide range of potential causes but I'd start with the turbo. If you're increasing the boost and seeing no improvement in power then it's quite possible you're simply at the limit of what the turbo can support. Without knowing exactly what the turbo is, it's hard to offer more input but the GTX4508 as an example is rated to 1200 hp and if you're at 1090 whp then you're probably there or thereabouts depending on the dyno. Research your turbo more, check the compressor map, and also measure the turbine inlet pressure. These will all guide you as to how the turbo is performing and if it is a restriction.