Hi Lorne,
While I did tune Monty in three key stages over a period of time (exhaust, inlet manifold, cams), it's not always practical to go to the rolling road to test each change. However, in very loose terms and based on everything known about tuning the Duratec (which is a lot), a 15 - 20hp gain can be expected from each stage.
I can also confirm that while the old school narrow band closed loop correction offered by the Visteon ECU will cope with the extra flow from a decent exhaust (stage 1) without any calibration work needed, that's its limit before you'll need to start making changes to its fuel tables. As soon as you move to stage 2 (ITBs or FF inlet manifold) you'll need to find a way to add more fuel to match all that additional air, if you don't the engine for sure will fall flat on its face!
There's nothing wrong with the Visteon as such, it's just tricky to tune, but I believe Rog has that one covered. However, I still think he'll find 185hp will prove to be it's limit, so while fine for stage 1 & 2 my guess is even the smartest tuner with the best software will struggle to take things further using the Visteon. My solution was to fit a stand alone ECU as I knew I would be taking Monty north of 200hp, at which point (stage 3 - cams) will reveal that the standard injectors are not really up to the job. If you stick with the standard injectors over 200hp you'll be pushing them over 80% duty, this is far from ideal because as soon as you get close to or into the 90% duty zone fuel injectors tend to become unstable. This instability could easily result in a momentary but dangerously lean condition under full load, and calibrating the old Visteon to accept bigger injectors would get super complicated, if not impossible?
If you then add a ported head to the mix taking the engine to stage 4 and start making over 220hp, it's also advisable to increase the fuel pressure, as I understand it the standard fuel pump should have sufficient flow to support up to 260hp so if you're making anything from 220 - 260hp all that's required is an uprated FPR.
However, I'll be testing this theory when I fit the gas flowed head
