Upgrading 1968 Anthony Pool and Spa

I have an Anthony pool/ spa combination built in 1968 and never re-plumbed underground to my knowledge (I have owned the home since 1985) The pool motor/pump/filters*have been replaced and reconfigured over the years above ground and the total system works the same since I have owned the home. *The connected spa has three basic, untrimmed holes which fill the spa and when total system is filtering: the water runs over the spa dam and into the pool and refills underground through the holes in the spa. The 2 of 3 small intake air pipes of the spa jets are above ground, approximately 1/4 - 3/8 diameter (one is capped above ground)* When the spa is heating these pipes emit a loud noise ( the same since I have owned the home)* The pressure of the water entering the spa when heating the spa alone is not dramatic…. *
1. Whether to be cautious about increasing the pressure of the water as it heats/circulates in the spa when the effect of increased pressure on the original plumbing underground (above ground is exposed PVC) cannot be seen.
2.* Whether, when the pump that is being considered is an Inteliflow Variable Speed Pump (about $1400 installed)
and Pentair tells me that it should be alright if it is run it at a "very low speed" and although I do think putting in this pump and running it at a very low speed will not harm the original underground plumbing, would running this pump at this very low speed will have an appreciable affect in making the jets stronger.
3. Whether there should be concern that this Inteliflow pump, which can be put at different settings above the "very low speed" as recommended for an old system, can inadvertently be set the speed to a high velocity/speed.
4.* Whether the air-intake valve mechanisms can be replaced or modified to reduce the amount of noise when the spa is heating/circulating. From what I observe,* the pump itself does not determine the amount of noise at these tubes. Perhaps there is some way to "muffle" the noise without cutting off the air… (The ends of these tubes are above ground but under a grate at deck level)

I would appreciate advice ! Thank you * * *

I'm not entirely clear what your question is. Are you asking if it's a good idea to get an Inteliflo pump, given the issues you raise in 1 - 4 above?

If so, I'd certainly hesitate. All the VS / VF pumps are the max size motor used in that pump line (Whisperflo in the case of the Inteliflo) coupled with a speed controller. All are capable of running as a 2 HP or even a 3 HP motor. Such pumps can be, and are, accidentally run at overload speeds for a particular pool.

A pool like yours, built in 1968, may well have iron or copper pipes under ground. And, accidentally running the Intelliflo at max could definitely overload the pipes.

You may be operating under the influence of a common error in thinking about pumps and piping, namely that you can overcome the problem of undersized piping with oversized pumps. You cannot, and should not.

Fix the pipes if you can; match the pump to the pipes you have and not the ones you wish you had!