Exhaust Options

I just wanted to inquire which exhaust systems either full or slip on are available for the Honda Silverwing 600 scooter. I know most have gone with Leo Vince and they are definitely tried and true for performance gain, build quality and beauty.

I would personally like to see what is available even to other countries outside of the US where scooters are even more prevalent.

I am looking at the GPR slip on speed cone that you can buy off of ebay currently for $350 - I've inquired as to why this exhaust doesn't replace the header piping and they replied telling me that it was unnecessary to do so and that no more power could be unleashed. They also claim a 4.5HP increase over the stock system.

From what I understand the Leo Vince is worth about 2 horsepower on the dyno and they provide for header pipes and muffler.

I am more concerned with maximum output and not sound so I would like to know what input anyone else has on this subject. Does the stock silverwing exhaust have the catalyst built into the muffler - I wouldn't mind switching to a pipe for off road use only until it is time to run through emissions again.

Scott

Thunderoad exhaust is available in the UK here:
https://www.pmtuning.co.uk/Merchant2/merchant.mvc?Screen=PROD&Store_Code=PT&Product_Code=01-SCOM_6PO
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Malossi Exhaust is here:

http://www.malossi.com/Catalogo/Cata_Main.asp?Marca=150&Modello=MO/HOSI600&Famiglia=0&CodArt=3212283
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Leo Vince Exhaust System is here:

http://www.leovinceusa.com/cart/search.php?Model=Silver%20Wing&Make=Honda&Year=&Line=SCOOT
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Gianelli Exhaust is here:

http://www.giannelli.com/eng/prodotti/details_pro.asp?id=459