I am looking into getting the Helix combo Uppipe and Downpipe shortly. The only power adder I have currently is a Greddy Evolution cat-back. My question is - will I still see good performance gains from this combo with the stock midpipe (and cat)? Or do I need to get a midpipe with a hi-flow cat to see good gains? I don't want to go completely catless because of emissions. I know there are a few midpipes out there with hi-flow cats in them (random technologies for one). Is it worth getting the up and down pipes without a new midpipe? Also, how much louder will my car be with the up and down pipes installed? Thanks!

 

If you get the helix combo, you will be catless. The helix downpipe gets rid of two cats. If you want to keep one cat, you can get a downpipe that only eliminates one, ScoobySport makes one

As far as how loud the car will be, you have one of the more quiet catbacks on the market so you won't be terribly loud.



:banana:

 

stromung just released a divorced wastegate 3" downpipe which is pretty affordable.

Bosal also makes a similar setup but in 2.5".

The bosal can be had already jethot coated from chargedperformance.com

I have the helix up/down pipes with bosal catback and it's great for driveability. No bucking, and picks up from 1500rpms, no more having to downshift.

 

The Greddy exhaust piping is 80mm (about 3 inches), so I probably want to go with a three inch downpipe also, right? It sounds like the stromung is the way to go (3", divorced wastegate). What are the specs on the ScoobySport?

 

i've got helix up and down pipes
they get rid of all your cats

you'll love it
it'll be like driving a new car
don't worry too much about sound, you have one of the quieter catbacks

i run an apexi catback and its loud, but i've heard louder, and cops never even look at me, and i have overly tinted windows, + my town has ***** *** cops, sooo.. you should be fine

btw, are you installing yourself?

 

the helix is 3 inch all the way as well

 

the scoobysport dp gets rid of only one cat, 2.5 inches, and bellmouth.
even if you just a dp that only gets rid of one cat it still is the main cat. the 3rd cat is not very restrictive at all.

 

The guy who bought my greddy evo exhaust has the helix uppie/downie combo. It's only slightly louder than with all the cats in place.

 

With helix up/downpipe combo you will be 100% catless. You might want to check your area to see if you can get away with that come inspection time. In PA, I would get red flagged right away.

 

Thanks everyone. I know that I can't get away with not having any cats, so I have to at least keep the stock midpipe. I'm looking for a downpipe that only replaces one cat with the bellmouth design. So far, the Stromung has sounded like what I'm looking for. I'm not really worried about the sound because the Greddy is very quiet. It's almost a little too quiet, so I'm looking forward to getting rid of two of the cats.

 

you can always go with a high-flow cat instead of the stock.

its not legal, but its better then not running any cats

 

I'd rather stick with the stock midpipe and stay legal...at least for now.

 

Yea what he said, just replacing the uppipe is illegal. Replacing anything that removes a cat is completely illegal.

 

Well, at least I will have one cat in there, for the visual inspection. If they want to dig deeper than that, then so be it. I mostly want it in there for a little bit of sound suppression (sp?) and to keep it from smelling.