New Mustang, How can I find out what mods have already been done
 

Recently bought 2001 Mustang GT 'Vert (Auto) unfortunately but just happened to stumble upon a good deal at a dealership. It has a K&N CAI and I know from the sound the Exhaust is definitely not stock. I am not a gear head by any means how could I go about finding out what type of exhaust is on or if the previous owner put different gears in etc.. If possible. Thanks! Will be posting a bolt on thread soon for advice

Hi, congrats. The previous owner would be your best bet on gettting the info on the mods done on your car.

Looking around is your best bet for bolt ons. The exhaust probably has a brand label on it so that makes that easy. As far as gears, perform a differential service and I suppose you could count the teeth on the ring and pinion gears and do a little division.

Thank You Captain Obvious!

OP please do a search on here before posting a New what bolt on's do I get thread
And if you post pics of the engine bay and the exhaust allot of us can tell you what you have just by seeing the parts
Gears you can count DS rotations Vs one revolution of the tire if the DS rotates 4 times for one full tire revolution you probably have 4.10's if it does 3 3/4 turns probably 3.73's
Or you can pull the cover look for a # on the pinion gear or count the teeth on the ring gear and divide that # by the # of teeth on the pinion gear ex: ring gear = 41 teeth and pinion = 10 teeth that would be a 4.10

I figured out my car had gears from driving the speed limit, and traffic would back up behind me lol... Without a tune/calibration install your speedo will read higher than what you're actually going. Nothing scientific about it but it gave me a heads up.

New Mustang,How can i find out what mods have already been done.
 

Sorry (Mr. Bramas), misunderstood my suggestion. 907GT stated he is not a gear head. So, it is not obvious to him about checking with the previous owner. Most of us ask questions, because it is not obvious to us. Or we need some help in understanding a issue or problem. Everyone is entitled to there own opinion. It seem that is not obvious to everyone on this forum.

if the previous owner put gears in and corrected the speedo then you can match them up using Cliffy's calculator

http://www.paladinmicro.com/pmicro.php#

just drive and notice where the rpm's are at certain speeds then go on there and compare them.

Exhaust should have some sort of stamp on them if u wanna get under the car

For gears, hopefully the previous owner either replaced the stock tag on the differential with an accurate one, or removed the old one. That may not be the case though, my old one had 3.73's when I bought it but still had the stock tag on it. Mark the driveshaft and turn one of the rear wheels one full rotation while watching the driveshaft and counting the turns. However many turns is what your gears are. So if it goes a little less than 3.5, you probably have stock gears. A little over 3.5, probably 3.73's. About 4 turns, 4.10's.