Yeah, the only DP I know of that works with a high flow cat is made by RRE. Here's the link... http://www.roadraceengineering.com/eclexhaust.htm What state do you live in? Going with a catalytic converter is usually gonna be more expensive and less powerful than a straight DP

 

I live in Georgia. And I need to have a cat to pass emissions.

 

would a Hi Flow Cat still pass emissions?

 

good question! I did not think of that. Will the hi flow cat pass emissions?

 

What if I buy the downpipe that does not replace the cat and leave the stock cat on there? Will this still work and give me hp?

 

Another question, do I need to have an aftermarket turbo before purchasing a downpipe? Can I just slap on the downpipe with my stock turbo?

 

stock turbo is fine

 

But would a hi flow cat pass emissions? Also, can I put on that downpipe with my stock cat?

 

you wont pass but it is only 4 bolt on the cat so just put it back on for your test then take it off after. thats all I do other wise offer them like $50 more and they might pass you too

if it is that much of a conserne buy a Hi Flow 3 in cat and call it a day but catless it better for power

 

yes, it will give you some more hp if you get just the downpipe and save your own cat