I'm looking at doing the Edelbrock 2.5" collector mod in my 97 GSR during this holiday break from school. I'm also looking at replacing the stock 2.25" cat.
Any suggestions on which 2.5" cat I should go with? I was looking at the Magnaflow spun metallic 300 cell cats, the type Dave from SMSP sells. Or should I stick with the oval style? Any suggestions?
Also, since I'm in california, trying to still pass smog, should I go with ceramic or metallic?
Also looking to replace the 14" resonator with an 18" magnaflow resonator, is it better to place it closer to the rear wheel bend, or closer to the front, right behind the catalytic?
Also, where can I get flanges, 2.5" stainless steel flex piping, O2 bungs, etc for cheap?

 

SMSP 2.5" 300 cell-currently on my car


My old SMSP 2.25" stock length


I have been very happy with both of these from SMSP.

 

cut the collector at the merge, weld in a 2.5" flex pipe and attach a 2.5" universal magnaflow cat with a thick 3 bolt rear flange. remember to test fit the rear and tack it attached so everything lines up right. i also have an edelbrock header with this done, one of the best low cost hp mods you can do.

however this might cause issues in cali since the whole reason edelbrock is legal is because it uses the factory system.

 

if u wanna stay legal you cant go with a universal cat. new law requires that the cat u get have a stamp that indicates that it is for that car. like carb and EO number found on intakes and headers.
summit racing has cheap flanges used some of their stuff for my exhaust set up...quality is ehh 8/10 but you get wat u pay for overall good

 

that's what i thought. so in cali if you mod the edelbrock it becomes non factory AND all the direct fit carb legal cats use the same stock flange it already has