Any Mods Regretted!

I'm not all that impressed with my Pro Chamber. It gave me that deeper sound I was wanting only a little bit though. In the soundclips you can't even tell the diff between the stock setup and pro chamber. I am somewhat satisfied but wished I got the cat delete or performance cats with it.
 
I'm not particularly happy with my JET chip, I wish I held out and bought the Diablo in the first place. (I'm working on getting one used now...)
The JET does make a difference in throttle response but thats about it that I noticed. If it were 50$ that would be another thing.....200$....not worth it IMHO. (Altho it is good for people who are worried about voiding warantees or just want to get ride of that Drive by wire feeling...)
On the other hand I am extremely happy with my SLP loudmouths....
 
I regretted getting aftermarket wheels from my dealer when I bought the car. Should have known I'd want to go wider in the back and take my time finding my favorite style instead of having them grab a set off another stang they'd added them to. Now that I have the wheels and tires I want, I will be selling the ones I got with the car for a fraction of what I paid for them.
 
My JBAs... when I first got them, I loved them because they have the deepest sound I have heard for any after market exhaust for the mustang. But, the only thing I didn't like was that they were just not loud enough, so I followed the fad and got SLPs. And, darn it, they are so friggin loud and sexy!!!