I recently fitted a pair of Motorola tweeters bought on Ebay for £2.99 inclusive of delivery. Fitted Smart's original bass bins bought for £20 including high spec speakers. Wired the tweeters to tweeter output on the Grundig cassette radio that came with my 450. Amazing sound. Crystal clear high notes and the loudest thumping bass at this end of Banchory.
Drives a Smart Cdi - 65 to 85 MPG
I added better speakers and amps and my system sounds much better than the original tweeters and bass bins.
I would be interested to hear the surround package also
I'm a big boy and I like my toys