1. TIPs do not "give" hp, they release the hp otherwise wasted by giving the turbo a larger opening to suck through. Lower half of the factory TIP, made of metal, is squashed at the middle, having less than half of the section area of the Forge TIP
2. Upper half of the factory TIP, made from soft and heat-vulnerable rubber, may crack at the DV or PCV or N75 fittings
3. After fitting my Forge TIP (I already had larger pipe to airbox), turbo spooled a bit quicker and the engine gave the sensation of "free breathing". It might have produced 0 hp more, but the driving quality improved
4. Noise does not increase. On the contrary, after remap, large air intake pipe, large TIP, 3" downpipe etc but still with factory cat-back, engine sound had diminished. Now it sounds at 4000rpm like it did at 2000rpm previously and below 3000rpm is nearly silent. From 4000-6000rpm is makes a deep pleasant rumble like a small V8. Mark my words, in case of a 1.8T harsh engine noise associated with chavved-up cars and boy-racers is 99% dependent on cat-back exhaust, and if an aftermarket exhaust does not provide a strong hp increase it's not worth the money and noise
~Nautilus