I am going more for sound considering 305's arn't really much of a power plant.

and mostly i dont want to ave to mess with anything

which gets me to my q....

i hear clearance issues with LT's but nothing about shorty's so... my question, which, if not all shorty's will fit without any modification? and how hard is the install

if this is needed, 89 firebird 305 700R4 i have a 3" I pipes i do believe
which i am changing eventually

 

Some sets are more difficult to install than others... they are made by Hedman, Hooker, Flowtech, SLP.... the list goes on.

Look for a set for a 82-92 Camaro/Firebird, and it should fit your car just fine.

 

i've run jet-hot coated hedman shorties and had great succes in my maros