Well, let's see here....I'll list in order my mods I have installed myself and consider to be the best bang for the buck mods.....I won't be scoring these as I think they all absolutely rock.
1. Clear corners - not one problem....followed the DIY and it went very smoothly except for breaking one tab, but it didn't affect putting back together the headlights at all. Best visual mod right out of the gate.....and it's the cheapest one you can do for the visual impact you get.
2. Misc DIY's such as fog light mod, gauge overlays, door chime mod, sub mod, matching silver interior pieces, etc....no problems at all except I was scared I was going to break some pieces trying to pry them loose. Now that I think of it, I did mangle one of my original window switch covers with a scredriver, but since it got replaced anyway, it didn't matter. Again, nice and cheap quality appearance and convience mods to set yourself apart...
3. B&M STS - my first install where I had to take apart anything significant. It went much more smoothly than I thought it would.....the only thing that concerned me was that the B&M STS base doesn't fit around our shifter plates without some grinding, or bending of the shifter plate, which is a bit of a pain, but no big deal really. Great for the improvement of the shifting
4. Injen SRI - Not one problem at all......easy install once I figured out the best way to get the filter past the battery was to take the battery out first. Still one of my favorite bang for the buck mods. I did get the PO171 and 174 CEL codes for a while in cold weather, but once I cleaned the MAF with electronic parts cleaner, and situated the MAF in the stock orientation, all the CEL's disappeared, never to return...yet anyway. Very nice gains in both sound and "seat of the pants" feel.
5. Injen exhaust - a no brainer.....if you know your left from your right, then this one is easy. Again, great sound and gains, especially when combined with the SRI.
6. RIPP Polyurethane Front Mount Insert -I had a member here that works for a Hyundai dealership do it.....the pressing the insert into the stock mount bracket was what I needed......that was the hard part. The easy part of simply reinstalling the whole assembly I did in 5 minutes. Not one problem with this install. Helps a fair amount with eliminating wheelhop, as long as you also remember to drop the tire PSI at the track. In retrospect, a full solid mount would work better in my estimation.
7. Nick Boers F/S Lightweight Crank Pulley - Yep, I chickened out and paid a shop to install it.....one hour later, it was done perfectly. Cost me an hours labor at shop rate, but I didn't get my hands dirty at all, which kind of sucked actually.....next time, I'd tackle this one on my own for sure I think. Definately a more linear feel to the uphifts and acceleration.....the Tib doesn't feel any faster, but it seems to rev a little faster when accelerating.
8. Eibach Pro Kit Springs: I did these with the help of an impact wrench and my brother in law......very easy to install, but of course I had a local shop do the hard work of compressing the springs and swapping out the eibachs on the stock struts, so no spring popping either due to them not seating properly. We put the strut/springs combo back in the car with no issues whatsoever. Much stiffer in the corners.....too bad the stock struts aren't up to the challenge.