Where did you get that exhaust. Never heard of it...

Dutch i think, used it on yz144 enduro and yz 250x, great linear power.
Van hasselt exhaust. It is handmade

OK, thx. will have a look ...

The XC/GP models comes with the same part number parts!

I think this pipe is a custom pipes for this 2 models...

Not GNARLY, not FATTY...

BE86001GG-CLJ-1 EXHAUST PIPE (EC)

BE86001GG-CMZ-1 FMF EXHAUST PIPE (XC - GP)

In conversation with two dealers, one here from Brazil and another from the USA, both almost say that the pipe that equips the GP model is an FMF FATTY!
It comes in the GASGAS GP for greater indication for thisbike to the ENDURO FIM...

It does appear to be a "Fatty" profile pipe but it is not a Fatty constructed pipe. I can tell that by weight difference in the hand. It's most likely GG's version of the FMF Factory Enduro pipe for the Austrian bikes. Basically a Fatty profile pipe with the heavier side wall material most people associate with the FMF Gnarly.

Thank you. Logically the more race oriented GP would need a pipe giving more power and over rev so I also assumed its a "Fatty". But it isn't. What you say seems plausible.