from round to slot port

I am running a pioneer premier ts-w2000SPL in  a ported enclosure, (1.75 cu ft, 4inch port 6.5 inches long) all pioneer specs. Sounds great, BUT, I would like to get rid of all the "huffing" from the port. Lining the box and aero ports helped but didnt get rid of it completely. Will switching to a slot port help, and if so, how do I calculate from round port to slot? Will it it increase output at the same power? (RFbd500)

Try this minimum vent diameter calculator.....it's included in a bunch of other calculators here.  You'll be surprised at how large that calculator is going to say your vent opening should be.  A good free software program for converting port shapes and general box building help is WinISD.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

thanx