Put it on a dyno or ask the builder. No one but your builder knows exactly what it's set up to do. Nothing but a dyno can give you the answer your looking for.
Most of the time a stock aftermarket piped bike with a good suspension is a beast in the trails. You may want more power but I would go stock with suspension before I jump straight to major mods. Stock aftermarket pipes plus 4 timing
Ditch airbox lid or airbox all together