Get the Takeda - it is definitely louder than stock sound generator; mine starts to roar around 2500rpm. HP increase? It's just an intake man - just for the sound.
Apexi Throttle Control does make a huge difference as well - I think I got mine off of ebay for around $140 (new and shipped from Japan).

 

Keep it OEM. Oem already have sound and it give our 3.5L engine more than enough air. Plus these aftermarkets intake are made out of aluminum or steel. It will stay hotter and keep heat trapped longer than the oem plastic. Overall to stay oem is just the smarter choice. If you want noise.. I suggest you get a full cat-back exhaust system.

 

I have the takeda and I'm very happy with it.

 

Sorry, old thread, but opinion on the K&N the same? No performance gain? ANd I'm hearing the 2015 GS 350 already has cold air intake?

 

Factory intake will run the same temperature air as a "cold air intake" system; so in that regard, the factory intake is the same as a cold air intake. You are not getting any colder air with an aftermarket system; the air is still routed from above the grill and to the filter, just like with the factory airbox. All you are doing with an aftermarket system is removing the airbox and sound generator and opening your filter up directly to the engine in a cone shape instead of a rectangle. the result is a change in sound, not in performance.

 

Well ************ that blows... I mean, the sound part is cool, but was totally buying into the spec talk on both the K&N and the Takei (sp?) ones I saw. I mean, I'd take 13hp and 11lb... Crap

 

If only it were that easy. I have the Takeda Stage2 on mine and I love it for the sound. Didn't do squat for performance or MPG.