I've had my Smart Brabus for less than a month. I recommend a "Go Pedal" for every Smart owner, but it's a must for anyone looking to maximize performance. Anyone can install it. The cost is $300 and you have 30 days to test it out. It doesn't increase hp, but it really improves performance off the line. As one Smart owner told me, your "Butt" Dyno will feel the difference. By the time you get the jump on an unsuspecting driver, it's too late for them to react. There are 3 modes, 1. Race 2. Sport 3. Economy and Normal. Each of the 3 modes have 3 additional modes to allow just the exact power curve that fits the performance you need for the right situation. It comes with a control head that allows the driver to make the necessary adjustments, but the driver must not be using the accelerator pedal while the adjustments are being made.
The next mod I'd add is a Sila Cold Air Intake from Smart Madness. The air intake is $169 and you must buy the $69 silicone tube that keeps out the hot engine compartment air out and directs the cool outside air in. Smart Madness sells the two together for $219. You can have it installed for $150. The dedicated Smart website below provides step by step instructions on how to remove parts you don't need and install the parts you do need.
http://www.evilution.co.uk/engine/sila_451_induction_kit.htm
I'm not a mechanic, but I installed it myself. Everyone told me I could do it. I'm not sure if anyone told me it was easy, but if they did, it wasn't, but I'm glad I did. It's a royal pain in the ass to do, but I learned how to work on my car. Now I'm not afraid to try doing any modification myself. I quickly learned that I can't screw up my car, as long as I took my time and was fairly carefull. The key is having the right tools. It took me a couple of trips to Wal-Mart to finally buy everything
I needed, but it wasn't expensive and now I have tools to make additional mods to my Smart.
The challenge of working on a Smart engine, there is very limited space in the engine compartment to remove and add components. The best tool I purchased was a mini torx bit wratchet that's about 3" long for $10 at Wal-Mart. I could get into tight places with that tool, where most tools couldn't go.
Most people take a short cut and hacksaw the air pipe out of the engine compartment. I wanted to try and salvage mine, just in case I want to reinstall the cold air intake on my next Smart. It was a feeling of satisfaction when I was able to remove the air pipe without taking a short cut to do so. However, it didn't keep me from flinging it like a frisbee across the yard. Lol