im planning on ordering 2 flowmaster 40 mufflers for my 2000 ssei, i have someone who is going to do the instalation for free but i need the pipe demensions and muffler sizes, also im getting a magnaflow cat so i just need the right sizes so i can get it done right the first time

P.*. everything from the engine back is stock

Should be 2.5" all the way to the muffler. I think.

alright thanks. i took your advice on the 40'*, i just hope im not making a mistake by having my dad weld it on, even though he does an amazing job i just want to be safe but we will see how it goes. i was impressed by your 80 series and i did a little serching on youtube and heard how the 40 series sounds and it sounds nice and agressive.

actually 2.0 going into the muffler

Does that drop to 2" at the Y pipe?

Before you weld everything up, you may want to clamp it down and drive it. You may throw out codes with the cat and or you may not like the sound of the mufflers. Once their welded, you own them!

yes it does