Having read the theory I agree with it,the problem being I found the reality to be totally different.

I bought my X already with Akra's on I also use Akrapovic on the other bikes and IMO their the best in the world but one is always looking for something else,it took me nearly a year to get a decent 2 into 1 off ebay a Metalmule, I'd have liked an OTR but wasn't prepared to buy new because I knew it was a risk going to a different configuration.

Fitted the Metalmule and it looked great and the bike looked 100lbs lighter,from the moment I started the bike up I realised it was a whole new ball game,went and test rode the bike and it was like riding a totally different animal,it had gone from a bike that pulls second gear from the lights without a second of hesitation to a real old fashioned thumper.

Without putting too finer point on it I was horrified,I'm lucky in the fact I don't pay for fuel maps or dyno time and maybe with some fettling it may have come better but it wasn't where I wanted to go,within an hour the Akra's were back on and I blasted around the block and I was relieved.

Anyone going from a stocker will be pleased with either,if you own a 660r and green lane or offroad or going around the world then I'd look at a 2 into 1,if you looking for a more spritely motor with more get up and go then you'll be looking at a 2 into 2 and the bells and whistles to make them work.

At the risk of getting into the theory side have a look at MX1,thats the 500 motocross championship for those that don't watch they run single pipe systems because they need bottom end,now look at world Supermoto you will see the odd single exhaust bike but the majority want HP and revs and hence why they all run twin pipe systems.