What turbo PSI are moderate to heavily modified Coupes running on the road . I am thinking around 22psi would that be correct The reason i ask i was reading an article on the new Mercedes A45 amg M139 engine which is apparently is the most powerfull 2 litre standard production road going engine ever . 208 bhp per litre and running a standard 31 psi ?At 31PSI there must be room to go even higher Sound very high for a petrol road going engine and its amazing how engineering has moved on in the last 25 years . I remember back in the late 80s and early 90s the Cosworth Sierras in BTCC were runnung 36psi .In the beginning with that much boost the heads were lifting I know other engines run higher boost but i am talking about road based engines

I'm running low boost at 1.15 bar and a max of 1.35 bar. FC performance hybrid turbo. Boost settings are set at very safe. As its thrashed continuously.

I run up to 1.6 bar (23.5 psi) - this gives somewhere around 450-480 bhp, or 225 to 240 bhp per litre.

Not really related to coupes but my MK5 GTI can see 1.5 bar spike then down to 1.3 bar of boost. It’s down to less than a bar by 5k rpm as the turbo is quite small. This kind of boost would worry me when I had the coupe but is entirely normal for a stage two Golf. Maybe the boost pressures are getting higher as cars get more modern. Well until we all drive a big battery that is!