For those of you with intercoolers, you have the necessary supporting modifications for our Stage 2. Upgraded downpipes are optional for Stage 2.
Despite this, our Mustang dyno showed peak gains of +77whp and +40wtq on a Stage 2 1M with upgraded downpipes. These numbers were achieved with 91 octane as well. If you are running 93 octane, you will see slightly higher gains (although I don't currently have any 93 dynos on my computer).
We also offer Race mode for Stage 2, which allows you to run 100 octane. We also make this stage compatible for those running 91/93 with the addition of water-methanol injection. On 100 octane Race mode, our Stage 2measured gains of +96whp and +77wtq!
If you substitute water-methanol for 100 octane, the numbers would be about 10 less overall (in my experience). This is with 91 octane though, so 93 and water-methanol could produce the same numbers. Either way, you are looking at peak numbers of ~395whp and ~420 wtq on a Mustang dyno. On a dynojet, these could jump as much as +30whp (based on some Stage 2 Race N54's that we have dyno'd).