NewEdgeStang

so I recently just bought a 2004 mustang gt 5 speed from a dealership. it currently has 62,000 miles on it. the mods that I have noticed so far are a vortec v3 supercharger (no intercooler from what I can tell), rc racing injectors.(are they any good?), flowmaster exhaust, and a k&n CAI. I recently noticed that the speedometer is off by about 10-15 mph which I would assume means a gearing change. what gearing would this be? also, how much would this car be pushing horsepower wise? my main question I have for this topic is, how do I check to see if its tuned? Ive looked for a tuner everywhere in the car and cant find one, and the ecu seems to be stock. im not sure how I can tell for sure but I definitely want to find out especially since its supercharged. one thing I did notice is it still has the stock throttle body, which seems like it could potentially be an issue since it is supercharged lol. any info on this would be great guys. this is my first mustang but when I was growing up my dad had a 2006 gt and I fell in love with it! questions, comments, or answers would be greatly appreciated! thanks guys!

NewEdgeStang

I might also add that when I bought it, it didn't have a boost gauge. I added a pro comp boost/vacuum gauge and when I floor it, it reads 9psi consistently if that helps

Derf00

10-15% off on the speedo could be attributed to a different rear gear or taller/shorter tires, or the wrong gear put into the transmission for the speedo. Unlike mustangs 05+ that use the PCM for speedo calibration, older stangs could use a gear installed into the transmission where the speedo connects. If they had gears in there and then took out the differential gears but not the speedo correction gear, you'd be off as well.

As for the tune, if it has a supercharger on it, it has a tune. It wouldn't run at all (or would run like crap), if it didn't have the tune. Contact a local (reputable) performance shop and have them take a look at the car on the dyno to see what kind of power its pushing and what gears are in there while they're at it.

NewEdgeStang

thanks for the reply, I will have to take it to a dyno shop to see what im putting down. im going to be doing major suspension upgrades in the future. idk whats wrong with this thing but it handles like a boat lol