Just guessing, but how about a diverter valve, air filter, spark plugs, throttle body cleaning, and I know a fuel filter change made an extreme difference on my wifes 1.8T (73,000 miles).
Regular maintenance. How many miles? I reccomend the TB change, TB tensioner, all the other crap if it's around 60K and hasn't had a change yet.
Then, a TTDV, spark plug change, throttle body cleaning, new oil and fuel filters, synthetic oil, and using 93 octane all the time. And replace all the vac lines, hoses. And maybe a heatsheild for the stock airbox.
Also, a catback will increase throttle response and torque, not to mention high-end.
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