I think noise is relative, but right off the bat I'd say it's going to be noisier due to the newly added resistance with the spring-loaded flow valves, a LOT more plumbing that is also 1/2 wider, and all that. As the previous reply said, I also believe those are DWV fittings. I wouldn't replace at this point though, I'd go with it until it leaks or needs needs further maintenance then replace with Schedule 40 as you can. I don't see your SWG in these pictures, I may be blind though.
I'd check your pressure coming out at the pool. If it's too low, you could get some jet nozzle fittings to narrow the output and increase back pressure a bit, it might also lessen the struggle of the motor to pressurize all of that new space in those pipes.