Exhaust
Like all turbos, VW's 2.0T appreciates a free-flowing exhaust, so we chose a Techtonics Tuning (TT) 2.5" turbo-back system. It's a similar diameter to the OE system but our research showed that some companies are posting better results with a 2.5" system than a bigger 3" version. So we decided to see if we could do the same.
The TT exhaust features a downpipe with a single free-flow catalytic converter. It replaces the two stock cats, and while the emissions are unaffected when the single cat is warm, it's not so good on cold starts because the "warm up" cat nearest the turbo has been removed to improve flow. So a smog test is best conducted with a warm engine, rather than a cold one or one that's been idling for an hour.
The 2.5" TT exhaust system has less restrictive Borla mufflers, mandrel-bent stainless steel tubing and polished dual tips. The tips aren't anything special but in California where they disapprove of everything, we're happy to slip past cop cars unnoticed.
Sadly, we don't have any installation photos for the Techtonics exhaust because of certain technical difficulties encountered by our photographer (Jeff swears somebody messed with his camera!). However, it's a pretty simple process. You'll find it helps to have a reciprocating saw handy when it's time to remove the stock system, and we'd advise caution when removing the portion connected to the turbo - although our GLI is brand new we still managed to strip the thread off one of the studs into the turbo outlet (where the downpipe attaches to the turbo). It took hours with a die to re-cut the thread. This is a fairly common problem on turbo cars with the heat involved and the design of the studs, so take care.
Installing the TT system is simple if you have access to a lift. All the hardware is supplied and you simply clamp it together, hang it from the rubbers and tighten it once you're satisfied it's correctly aligned and you've allowed sufficient clearance front to rear.
Intake
Stock airboxes are designed with certain compromises. The biggest is noise - VW designed it to flow adequately while remaining quiet under throttle. They used a series of baffles to quiet the intake tract, but this represents a series of restrictions. However, they did manage to squeeze the airbox into the engine cover, making it compact and discreet.
Companies like Evolution Motorsports (Evoms) do away with the stock airbox and replace it with an intake pipe and an oversized, better-flowing, reusable cone filter. Heatshielding is also added to ensure the filter doesn't suck hot air from the engine bay.
Note: the kit shown is a pre-production version of the Evoms V-Flo. The production model will be molded plastic, allowing smoother bends, less weight and more heat resistance. While fitting the CAI, take care nothing falls into the turbo inlet and that the inlet is free of debris.