When we did the mini motards in Brisbane we bought silenced pipes from small wheel deals that got under the max db allowable for lakeside. Only thing though they played havoc with tuning for a bit so have to adjust jets to suit
or remove the muffler, and find a washer that just fits into the inlet of the muffler,
then slip it back onto the pipe and clamp it up.
this will restrict it a little, and quieten it down a lot.
The yx 160 and the GPX are different motors, the GPX 160 is otherwise known as the 160ho,155z and are also known as GPX and ZONGSHEN motors, the 155z and 160ho are both 155.7cm3 and the yx 160 is actually 161cm3 i believe, but give me a 155z/160ho before the yx. Clearances inlet .003 and exhaust .004
v2 head by itself is the better option, v2 head increases the revs and power massively. big bore kinda needs the v2 head with it to be really useful imo
Buy the head, put it on my bike and I'k\ll tell you how it goes. You buy the big bore kit for your bike. We can race. Loser buys the hot fogs (i take mine with mustard AND sauce, kinky ey)
Just bear in mind the differences in power delivery... It might turn out that a 4 stroke will deliver the power that you need where a 2t might be a handful in certain situations. What are you planning on doing with it?
^^ yep, until it catches fire, and spits out burning bits everywhere
there was a seller a while ago on ebay selling a cnc milled end cap that fits into most muffler tips, then locks in with a couple of screws.
this quietened them down 20% or so.