hey guys, i'm in s/j calif. I did my stacks with 4'' aluminized steel and powder coated them,there is quite a selection of colors to chose from,mine kida matches the truck,I did use the stock down pipe and chucked the muf. the resinator had 3'' in the front and 4'' out the back so I put it on the down pipe next to the transmission and put on a 4x4x4 wye then two 24'' s/s flex's and up with the duell cooling towers, I also put on s/s heat shields with 1/2'' perforation so the color shows thru,there is about 4' of pipe exposed above the shields, with a 75* ell on top to add that salami cut look,i'm trying to get some pics over the net to show off,most of the guys at our ram runners meetings here in san jose ca. have seen them they sound very nice, if I had the time I would re-do them with 5'' now that I know they would fit and sound even better[ maybe that megaphone tone]
good luck with your choice
JDMJOE