i have two pioneer 306c 12in subs in a 3.7cu box i have been told ported would be better
is this true
do i just drill a coupple of bug holes in the box to port it

ported boxes provide a higher output than sealed but only in a limited range of frequency- sealed boxes tend to be a bit more user friendly all round.
definatly DON'T guess a port size as you will end up with a terrible sounding sub. check the user manual for specs on port diameter AND legnth- changing either of these will be a disaster

They do like ported boxes better, but please dont just drill holes into the box. Generally a port is similar to a piece of PVC pipe, that is its a few inches long (4-8), by a few inches diameter (4-8).

Those subs like about 2cubes each tuned to about 35hz.

If in doubt www.mobileelectronics.com.au have a heap of posts regarding box size/specs for 306Cs. Just search away....