My girlfriend has a 2007 rancher 420, something in the exhaust is broken and makes a terrible rattling noise, I would like to get her a Hmf pipe for her upcoming birthday but I’m worried it will harm her motor over time, my question is do I need to get anything else (better air filter, programmer) to keep the quad running good? Not looking to gain power or anything, just tired of the rattling noise,

Another question:

I have a 2004 foreman 450 with a bore kit in it, and all the head studs have been heli-coiled as the previous owner pulled them out somehow, I would like to do exhaust, and jets, intake is done already, but I’m worried that putting more power will rip out the studs again. My question is will putting a bit more power into her run the risk of pulling heli-coiled head studs out?

Thank you for any and all advice.