As far as performance mods, the best bang for your buck is the Cold Air Intake (CAI) and hand held tuner combo with custom tunes from a reputable company such as American Muscle or Brenspeed. The both write excellent custom tunes for both the 4.0L.
A stand alone CAI will not net you much HP gain, maybe (3-5 HP) and is barely noticeable. I have an Airaid CAI, which does NOT require a tune. I drove around with a stand alone CAI for several months and felt minimal performance gain at higher RPM range. Once I had enough money saved up, I purchased the SCT tuner with 3 custom tunes from Brenspeed and was very pleased with the outcome. Once I uploaded my custom tunes from Brenspeed, I noticed the performance gain immediately. The custom tune really woke up my V6 and it felt like a totally different car. The estimated HP gain for a V6 is 15-20.
**Do NOT consider a drop in K&N air filter for the stock airbox. This will not get you any HP gains.
I hope this helps and good luck!
- 2005, 4.0 - Missing 2 cylinders :-/
- SCT Xcal3 w/ Brenspeed Custom Tunes
- Airaid CAI
- Pypes Streetpro Exhaust
- AM Front Chin Spoiler
- AM Quarter window louvers
- SHR honeycomb decklid panel
- Cobra R wheels
- Eibach Pro-Kit lowering springs
- Billet Honeycomb Chrome Front Grille Overlay
- Smoked tail lights & turn signals, Mustang 3rd brake light decal
- Raxiom sequential tail light kit
Last edited by kevinmalec; 09-17-2013 at 08:44 AM.