Plenty of 4 cyl engines easily handle well over 10psi. Many handle over 20psi....for a while :)

With turbo kits becoming available for the FS engines, it's only a matter of time before people begin pushing the limits of the engines. One guy will run 11psi, so the next guy will try 12, and so on. I bet we'll soon know what the tranny, bottom end, head gasket, etc can hold (this is assuming that everyone will be using the FM kit and upping the boost with no other tunning).

About 4 years ago there was a guy in Florida with a FS Probe. He was running 14psi of boost, plus a 30-40hp shot of nitrous. I conversed a little via email. . . Claimed he ran high 12's on slicks I believe. . . I cannot verify that, but I did talk with all the shops that did the work on his car, so I know the work was done, and his car was up and running for quit some time. It supposedly was also featured in a local publication down in Florida. . . As mentioned it will only be a matter of time for the true limitations of the FS motor are found as it is further explored.

I have also personally run 14psi on my own FS, but of coarse that was only a few days, before the poorly speced pistons on my car gave way AGAIN.

OK, what is an MBSP?

That technical diagram above doesn't show main bearing caps. . . the Protege FS's do have main bearing caps don't they? That piece you have circled looks somewhat different than the older FS in the Probes.

who sells the manual for $20? i thought they were $100+