The worst thing about the MkIVs' factory tires is how long they last. For the most part, they aren't bad, but with so many good alternatives out there, it's crazy not to try some. While we were doing tires, we also decided to upgrade the wheels. Several MkIV platforms came from the factory with 18-inch wheels and we thought an upgrade was definitely worth the small expense. We started our search at Discount Tire Direct's website. We have also been considering a brake upgrade, so we had questions regarding that and needed technical info on different wheels. We called DTD's order line and got answers immediately, with clearance concerns put quickly to rest. We went for TSW Montage wheels, each weighing 25 pounds for our 18x8 size. Finished in silver centers with a polished lip, they give the car a great look without being too overstated.
For tires, we chose Nitto's new Invo in 225/40. The tread design has always piqued our interest and we have been impressed with its low noise and high grip. They were shipped directly to us from DTD, mounted and balanced on the TSWs. All we had to do was bolt them on.
With the car connected to the ground, our next replacement/upgrade was obviously the braking system. We contacted parts4vws.com, who provided a basic upgrade to 12.3-inch rotors (up front) from the Audi TT and Hawk pads. The larger rotors require a different caliper carrier to move it out to the appropriate position. In the rear, we considered an upgrade to 10.1-inch brakes and calipers from the 337. Looking at the cost-versus-benefit ratio, we decided to stick with 9.1-inch Powerslot rotors and Hawk Pads to match the front.
The MkIV has good brakes to begin with, but when replacing them, the TT front upgrade is a no-brainer. The car stops incredibly, the Hawk pads bite much harder while also being easier to modulate. Even with the stiffer suspension, it's obvious the fronts are still doing the largest share of the stopping. If we were to go any larger at the front, we would consider a rear upgrade, but we're happy with the current set-up. We had the install done by Ron Wood at VW Specialties in Huntington Beach, California. This is a job most enthusiasts can handle in their drive way with basic tools, but Ron got it handled quickly and easily.
This next part may be the most interesting for the average enthusiast.
While we all know suspension and brakes are the most important upgrades, power upgrades are fun. We start with probably the only part that could be considered a real wear-and-tear item. VW's factory diverter valve can best be described as 'economical' (we probably couldn't print the worst things it's been called). We sourced a shiny new aluminum diverter valve from VF Engineering: a piston-type valve with a billet aluminum body that will probably outlast the factory turbo. The factory diaphragm-type diverter is prone to failure and leaking, leading to less-than-factory boost levels and so decreased performance. This is an easy mod that's well worth the expense, even on an otherwise stock engine. After replacing a couple of stock valves, it's nice to have components we know will be dependable.
For those tired of replacing those paper air filters, and looking for more power, we suggest the Eurosport Cool-Flo Intake system. Not only does the intake add power (five to seven hp depending on other mods), it also adds some intake noise. A reusable ITG foam filter is surrounded by a heat shield that keeps hot air away from the intake. Construction and all included hardware is top-notch on Eurosport's pieces.