149BT is only 4 x 18 Watts RMS and peaks at 4 x 50W, which is in line with most aftermarket head units.
The KTP-445U is 4x45W RMS and peaks at 4x90W, and if you're only use 2 channels, you can get 2x90W RMS. Definitely worthwhile if you upgrade your speakers, but it's probably overkill if you're keeping your stock speakers. If you do upgrade your speakers, though, most quality speakers need some type of outboard amp to sound their best, especially at higher volume. As for sound quality, as long as your amp is delivering the right amount of clean power, the choice of speaker will affect sound much more than the amp. The KTP-445U is really good in this regard, but it's not going to sound much better or worse than any other similarly rated amp for any given speaker.

 

The KTP-445U is useful in some applications but I wouldn't go through the trouble to use it in an s2000. It won't fit behind the radio and will need to be moved to under the dash or under the passenger seat. And after that, it would only be powering the two door speakers(in most caseses). You can get a good quality 2(or even 3 channel to run an additional sub)channel amp with 75-125wrms per channel for a little bit more.

 

Respectfully disagree on the 445u. It fits very nicely behind the the passenger dash, which makes for a very nice stealth install and provides plenty of power, especially when bridged to 2 channels. There is also an updated $99 KTP-445A that is plug and play with Alpine HUs.

 

I just picked up the 147BT instead after much debate. The 149 didn't really offer me much difference.

 

I have the Alpine CDE HD149BT in my S. It works great but I have a complaint. If the unit is off, the clock doesn't show. I suppose I could leave it on all the time and turned all the way down but that bothers me. I'm using the Modifry interface for the dash controls, too. That works well.

 

Good to know. Wee you able to get the orange an black color scheme to match the S? I believe it only has partial color variability.

 

Just finished installing my 147BT. I had some aftermarket Ipod connector thing in there at the previous owner had installed that I had to chop all up to get out. What a pain in the ass. The foam around the shifter also disintegrated as well. We'll see how much louder/warmer it is now near the shifter.

For now, the mic is mounted on the bottom to the left of the steering wheel. I don't think it's in a place where I'm going to hit it. The wire was long as hell so I've zip tied it in various places to keep it up.

 

I've been using the 149bt in my car for a little over a month or 2 and so far it's good. It has a built in audio processing unit (i believe) and makes the current speakers sound better.

As far as the color change, you get red, green, blue, or orange