While I haven’t owned it in almost 15 years now I had a 3.5 MSP with stock internals running 10psi with pretty much every bolt-on upgrade possible including improved intake, hard pipes, FMIC, SAFC, electronic boost controller etc. I did everything except rebuilding the bottom end with forged parts. I had the car dyno tuned and was putting out 203 whp at 8lbs of boost. When turned up to 10 with that tune in it I would put down 211. I also had an aggressive tune running 12.5 lbs of boost that I would put in for the occasional ty with real $ on the line that was good for 222 whp.
I wouldn’t run that engine at anything higher than the 8lbs on stock internals if you plan on driving it daily. I ended up letting the car go because I felt like I reached the limits of what could be done without completely rebuilding the block, adding the LSD and upgrading the turbo.
I actually found my way back to this forum today to start looking for another one to build into a track days car and reignite my passion for the Mazdaspeed brand. As soon as I sold that car I regretted it. The worst part is that the girl I sold it to, drove it into a tree about 2 months later and totaled the car.