as for the glass packs they can be restrictive but you can get most of the sound dampening out but just putting your hose in the exhaust pipe when the car is good and hot. this will destroy the material and then you can just rev it up to get the excess water out. dont use alot of water just under a gallon or so. make sure the car is running when you put the hose in. this will make it a little loud but the flow will be better. as for passing smog if you remove the cats then i think you will run into problems. you might be able to get away with replacing the cats with high flow cats. hope this is a help. oh and the mufflers just talk to the exhaust shop they should be able to help you with this.