They are really cheap tires....
Primewell PZ900's.... I like them cause they make a 255/50/17 which I run on stock rims all 4 corners. They are AA traction and A TEMP with W101 rating (168 mph 1819lbs per tire load index)
They are currently $129 each at Firestone will be much cheaper on the 11th.
Even the way I drive I have been able to get 30,000 miles out of a summer performance tire.
http://www.primewelltires.com/PZ900.php
I think if I did anything else I would bend single 3" pipe myself and weld on a collector so I could try single straight pipe after the Y. It would be loud but should also be AWESOME!
With the damage to my stock Y pipe I bet my car was very similar to your freinds washer set up.