GIAC couldn't keep its hands out of the rabbit's ecu and its $395 software can take your car to 149whp, with nearly 20 lb-ft more in the mid-range and a higher 6600rpm rev limit. Giac also offers its flashloader option, so you can upload different programs for valet mode or 100-octane fuel with a handheld module that plugs into the obd2 port. Cracking into the euro scene, greddy has an exhaust for the rabbit using 60mm (2.36") piping with dual 76mm (3") tips, and retailing for $769.
Unitronic sells three stages of software. Stage1 for 91-octane retails at $350 and should be good for about 150whp and 169 lb-ft on a stock car. Stage1-plus for 93-octane retails at $400, while its $450 stage2 software is tuned for a car on 93-octane with an intake and exhaust. The company claims improved throttle response and smoothness over stock.
The secret Weapon intake system from Weapon*r features mandrel-bent 6061 aluminum piping and an sw1 high velocity air filter for $259.
$1000-2000
APR sells a fully polished 2.5" mandrel-bent t304 stainless exhaust with cnc hangers. It retails for $1099 and comes with a lifetime warranty. They claim 20hp and 20 lb-ft peak gains.
$2000-Up
If you'd rather keep the car normally-aspirated, you could use evolution tuning's header and take your pick from several intake systems, cat-back exhausts and software. You'd probably be on your way to 170whp with plenty of torque.
For those wanting real power, c2 motorsports has developed its stage 1 turbo system featuring a Precision t3/t4 turbo, tial 38mm wastegate, stainless tubing, laser-cut 304 flanges, a cold-air intake, manifold cover, 415cc injectors (about double the stock size) and c2's own tig-welded manifold and software. It also includes oil feed and return lines, t-bolt clamps plus other mounting hardware, and will bolt to the factory exhaust.
At $3500, this kit reportedly puts out a safe 220whp and 237 lb-ft at 8psi, and C2 is currently developing an intercooled stage 2 as well.
After extensive testing, NGP racing has discovered the stock pistons are the weak link in the engine, and that customers shooting for over 250whp really need to consider stronger engine internals. With NGP's forged aluminum pistons and connecting rods, the firm offers a turn-key system for $7500-8000, depending on options (the pricing includes labor to rebuild the motor). To create the ultimate 2.5 turbo, ngp uses its rods and pistons with a c2 tubular manifold, custom 3" downpipe and exhaust (which is a modified apr gti system) with catalytic converter, 3" intake, 2.5" piping to a modified eurojet side or front-mount intercooler, 3" pipe to throttle body, 440cc injectors, a smaller odyssey battery for piping clearance, 42mm external tial wastegate, APR R1 diverter valve and a custom clutch. Compression drops from 9.5:1 to a boost-friendly 9:1 and the turbo system uses C2 software. It's reportedly good for a whopping 350whp and with the five cylinder's wonderful exhaust note, it's got to make you think twice about spending an extra eight grand on a GTI 2.0T with half the power!