Universal Muffler And Oil Type, Hopefully this is in the right place lol Options

[mariosdarkworld]

Ok well i was looking at my exhaust system looks like i have two cats. Im guessing idk. Does everyone that owns an st have this weird thing that looks like a cat (sorry not to familiar with them) it goes right after the header. Anyhow i live in AZ so I dont need two I only need one. My question is what is a good size tubing for this vehicle and whats a good but not to loud muffler cause i was thinking MagnaFlow and 2.5 tubing.... Magnaflows pretty inexpensive and i heard it on youtube so i think i may go with that but i am open to suggestions
Next question is it says to use 5w-30 on the manufacture specs but this car is old and has 163k so I was told to use 10w30 in the winter and 10w40 in the summer. What are your guys opinion?? sorry, i know i typed alot just thought it was necessary lol P.S. It gets like 115F here in AZ for normal temp during summer:(

[playr158]

i believe all st's are california spec. i may be wrong though. thats why you have 2 cat's

WRONG

Some STs have 1 cat (like mine) + resonator

10w30 mobile 1 is a good oil