Don't worry about your exhaust Aaron, it will work fine.
There is no valve overlap with the HS 142-144F engines, take the valve cover off and you can clearly see there is a brief time both valves are closed (a degree or 2) at the same time so that settles that.
Actually, set your vale lash while you have it open.
Other than removing the stifling stock box exhaust, I can't see the specs on what you replace it really making any difference as long as it flows freer than the box, heck I use NON-EPA 2 stroke pipes on mine, without the catalyst part in them they flow pretty free, bolt right on and look cool for ~ $25.
I get the biggest performance boost by just replacing the stock plug with an NGK 7544 (CR7HIX) Iridium spark plug.
It is slightly longer so it actuality increases compression.
A better air cleaner helps a little but really just for looks ;-}
Another thing you can do is not direct the PCV hose back into the intake and route it into a 'catch can' but I haven't tried it, it just makes sense to me since those gasses are just waste.
Hope that helps ya Aaron.