The bottom end is probably missing from your 5 port as it is still real tight. Mine had a similar feel when new. Make sure you are using the break in shim - this will help a LOT !!
The 5 and 7 Port motors are legendary in their pinch when new. They do not entirely free up until you have put about 2 - 2.5 gallons through them. Then look out The 5 Port has heaps of bottom end for most applications. If running in a buggy you will most likely need to tame it down a bit with clutch, pipe or restrictor, depending what sort of track you run. The 5 port suits a tighter track with jumps just out of corners etc.
I run buggy at a track like this and use the 086 pipe, 7mm restrictor and 1mm springs with carbon shoes on my 5 Port Turbo and it is sweet