hi,

what is the rule of thumb for port tuning to gun for in SPL install? 45~48hz?

cheers

If you have a meter to test, start at around 40hz, find your peak and burp. Cut about an inch and repeat untill you begin to drop in score at the peak freq.

Much of it has to do with the size of the area you are pressurizing. Tiny cars or vans with walls tend to have a higher peak, large SUV's with below the window line enclosures tend to peak lower.