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Discussion Starter #1 (Edited)
Here’s my dilemma. Car is at the body shop right now and it looks like the exhaust will need to be replaced. Body shop does not want to be involved in installing headers. Can’t blame them as it’s not something they usually do. However he has no problem with doing a cat back. I should be able to get them to R&R main cats also.

I was considering long tubes (Kooks) 1 7/8 (LS3) but my concern is twofold. One the logistics of two separate installs and possible overlapping parts purchased and the fact that headers are usually a bit of a flag for a dealer when dealing with power train warranty issues. So to make things easy I was thinking of going Solo cat back with HFC’s and a tune or Corsa cat back and Solso HFC’s Dealer might grumble about the cats but not as much as headers. If later on I decide to go with long tubes I could just order up the Solo or Kooks kit to mate with LT’s and sell the cats.

How much HP/TQ would I be giving up? I would think not much given the fact that most of the power is gained by ditching the 4 cat’s (09.5 GXP) and replacing with 2 HFC’s and it does not look like the cast manifolds on the LS3 are that restrictive. Any suggestions as to which cat back combo to chose. Solo you’re giving me to many choices…lol. I would like something that is not super loud but at part throttle or idle a passerby knows something is different about the car and of course angry sounding when I get on it. I really like the Corsa sound at WOT. Guess I like a little higher pitched exhaust note. If I go with Solo then I also need to decide on tips. Standard, 3.5 Twin or Square? Again it’s a GXP so the diffuser will accommodate all 3 styles to the best of my knowledge. I will also need a tune and understand VMS has a specific tune for the Solo cat and HFC combo?

Opinions and suggestions welcome.
 

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Vendor
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1,288 Posts
Hello Stibuki,
I am sorry to hear about your car being in the body shop! I can help you with whatever you need. The HF cats and cat-back will increase power in the 30hp range, more with a tune. VMS has a specific tune for our HF cats and cat-back kits. If you purchase our cat-back, I will extend the group buy price of $593.30 to you on the HF cats, rather than $698.

We also sell a catted midpipe, which uses our HF cats and is a direct bolt-on solution for the Kooks LT headers. It comes with a choice of any of our cat-back kits. You would have to get the Kooks headers. To be honest, the HF cats and cat-back make almost identical power, maybe just slightly less on the top end. The HF cats and cat-back would get rid of all 4 cats.

My suggestion to you would be to go with the Mach Cat-Back with the HF cats. This is a popular combination and seems to be exactly what you're looking for based on what you wrote above. The tips are your choice. The 3" quads come welded on. The 3.5" quads come separate and have to be tack welded. They (the 3.5") only fit in the GXP fascia. Call me anytime at 516-655-9002 and I would be glad to help you.

Steve
 

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CCG8 / FLG8
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You will not go wrong with the HFC and catback system. it is very impressive.
 

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You can't go wrong with any Mach cat-back and a set of HFC's. These are direct bolt ons and don't require a tune to run although a tune is recommended to get the best gains. guaranteed grins
 
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