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:(

[GotToyota]

For oil, I'd recommend Pennzoil Platinum. It is by far the best shelf synthetic you can buy (with the exception of Royal Purple). I've tried Mobil 1 this oil change, and I have to say it's worse. It seems to burn off more, and my gas mileage dropped. I only used it because Wal Mart as out of the Pennzoil.

I'd say stick with Pennzoil. If you want some good info, check out this forum here:

http://www.supramania.com/forums/forumdisplay.php?f=108