Hi,
Don’t be so concerned with numbers, it’s how much you enjoy your ride!
Since you asked, I’ll answer..
Average drivetrain loss is 15% less than Gross HP to RWHP, placing your 2014 Coyote’s 420CRANK or Gross HP loss at -63RWHP (420BHP *15= 63RWHP, so you’re planting 357RWHP (stock), which isn’t too shabby (which also PLANTED that shi* eating grin on your face when you bought it-remember...?). Can a Coyote do better? Hel* dam^ YES.. Drop a Kenne Bell on it and clear for takeoff!!
Realistically..I’m guessing...low mileage, you’re running a C & L Racer CAI, and ran an upper tier free flowing exhaust (no Longtubes) with an X pipe Cat delete, a correlating Catback and a “high” (93 Octane) Bama Tune.. you should be be planting just shy of that 15% drivetrain loss- right around 400RWHP.
Keep in mind every car is different.
If the car plants it well and doesn’t skate all over the road, then you might consider the most cost effective Mod, (below) with some Zerk fitted Poly rear
control arms & some stickies out back should nail 60 MPH in 3-1/2 sec’s, May gain a tenth if you lose the back seat! lol
Improve acceleration in your S197 with this Ford Racing 2010-2014 Mustang 8.8" 4.10 rear end gear kit!
lmr.com
Great Car! Enjoy every second of it!
Best!
-John
P.S.: Don’t forget about any extended power train warranty(ies) you may have, don’t want to void them, if not- have at it!.