Deicide

Has anyone ever done this? I've tried to search for a set-up like this and might be search impaired.

This would be in a 07 A6 Z51....just thinking about mods for now.

I am actually looking at the 'street-legal' package here:

http://www.westcoastcorvette.com/p-2...07-c6-ls2.aspx

Not opposed to long tubes. I also know I won't see full potential without going with them. But would it choke it off enough that it would be so minimal of a gain it would not be worth the $ or time?

Edit: I guess I wasn't very clear and reading back through this I see where people misunderstood for the most part what I was asking. So an edit.

When I mention not being opposed to going with long tubes. I meant that I am not ruling them out. But I am wondering more so if going with a mild cam and ported heads and STOCK exhaust manifolds would be virtually pointless. I know that the LT's will yield me more power. But out here in CA visual is part of the smog check. I know technically changing the cam will make it not pass smog as well, regardless of the sniffer test results. But a cam swap is not detectable for the visual portion (if not impossible) to my knowledge. Perhaps I am wrong with that as well.

I figure doing heads and a mild cam might still pass sniffer. If I leave the stock exhaust manifolds on I won't need to worry about visual as well. While huge HP/TQ numbers would be great - this also is used as a daily driver as well. So need good street manners. So I don't expect to make anything huge - just would like something other than stock....for now at least.

Mike V.

Lately I've seen every variation of the same theme LTs & stock, LT, cam & stock. Now LTs, cam, heads & stock.THIS IS THE DEFININTIVE, END ALL TIMELSS ANSWER! MUFFLERS DON'T MAKE POWER. In the case of the stock C6 mufflers they flow pretty well (yes it's on the forum compared to others, SEARCH). The max you make is 5-7 horepower on mufflers over stock & this is also documented, with much more data showing less, if any. If you're worried about choking it off use LTs mated ot hi-flow cats, 3 X 3 X-pipe, 3" mids, paired down to meet the connects for the stock axle over for the stock muffs. MUFFLERS MAKE NOISE & IT'S BASED ON SOUND OR A PARTICULAR LOOK WHICH SOULD BE THE ONLY CONSIDERATION FOR ADDING THEM. Even the Z06 mufflers pair down to to 2.5" the last inch or two as they enter the muffler.

OP, please do not think I'm beating up on you, but this question has been asked & answered over & over. There's post literally on the same page of Tech today asking it.

corvet786c

If you are goin all out with this set up do it right the first time.

I cant speak for anyone else but a free flowing exhaust makes a diffrence with the power you make. The stock muffler has its limit thats why it is stock. Think about it.
If you are adding headers intake and axel back, you engine can breathe better exhaust better. Adding a cam produces more duration and more air to go thru the system. You want that air to escape your system as fast as possible to produce more power.If you are doin heads cam headers get an axel back system. The whole system has to compensate one another to work better. You wanna get the full potential out of your vette. Do it right the first time.

Mike V.

... show me the data with back to back comparios same car, same day, same dyno. Hypothetical info & conjecture is worthless. If you want to realize the full potential of the mods considered add a ported FAST 102 which is PROVEN to make 25-35hp. Add an underdrive pulley when cam go in, which again is proven o make 8-12 hp. The power level w/ the 2 mods would net min. 35 peak rwhp & more in mid range for less money. What mufflers is going to add that? That would be doing it right the first time.

Fore58

Not to mention, the Z06 axle back mufflers are great. On the dyno it made 5 more hp with the valves open. I had it done twice just to make sure it was true. And the sound is awesome to me.....but some people might think otherwise. There are a few sound clips. Do a search. Good Luck

Ragtop 99

Others have done heads and cam w/o longtubes to keep the car smog legal. I did it with my second LS1 camaro.

The stock muffler is not the problem for a mild set-up. I'd look for a set of used Z06 manifolds to use instead of the stock C6 manifolds. Ported heads, FAST intake, UD pulley, and a matched cam will achieve a very good result in your A6 and be smog legal and work nicely with a stock torque converter.

Deicide

Well, what I was asking I should have been more clear about when I mentioned 'exhaust'. I meant the stock manifolds as well. So by that, no LT's.

Deicide

This is what I was looking for...thanks.

old motorhead

Stock muffs are not an issue on mild builds. As power goes up, they become more of a bottle neck. I saw 20 hp difference on my cammed LS3 with the NPP's open vs closed. I'm sure the closed NPP's don't flow as well as stock muffs, but you get the picture. The stock muffs don't flow as well as open NPP's either. GM noted a 6 hp difference on a stock LS3. As you add power, that difference will grow.

Also, loud doesn't necessarily mean good flowing. I had a set of Flowmasters on a supercharged truck that were obnoxiously loud. I measured 4psi of back pressure between the headers and mufflers (no cats). Switched to Magnaflows and they were actually quieter with less restriction.

Deicide

Not so much concerned about the mufflers as I am the stock exhaust manifolds. I guess I should have been clearer in my original post....I think I will go edit it now.

gunterwalker

You will lose some but I think your car will put out some pretty good power even with the stock exhaust. I know there are some cars that have SC's with everything else stock and are putting down some pretty amazing #'s.

Mike V.

then look for a used complete Z06 system, which will provide the least back pressure & best flow available, particular w/ Z06 muffs open. If you do decide on LTs, like I said earlier, hi-flow cats 3" X-pipe & mids paired down to 2-1/2 mated to axle overs for stocks. Either way a good hp option depending on other goals smog legal, stock appearence, whatever. Now stock LS2/3 manifolds will be extremely restrictive & head work may fall way short & be a questionable cost/benefit, on the other hand a mild will fair reasonably w/ Z06s, will work but suffer w/ stock, but not to the extent of the dollar vs hp on head work.

Deicide

FYI - I did use the search button. And all threads seemed to point towards cars running h/c but with LT's as well. I understand that my original post was vague. But in my perspective - exhaust doesn't only refer to the mufflers. There are other parts involved, mainly the stock manifolds. I thought by mentioning the LT's it implied that was the part (portion) I was referencing. Then again, I guess by a couple replies it wasn't that clear.

Deicide

I have considered the S/C route as well. Mainly this is all being considered because I already have one car I can't drive on the street anymore because I got nailed. (H/C/Nitrous/LT/ORX SS Camaro). So that does play into my thought on the mods I will choose out here in CA. I told myself I would keep it stock...that idea died about 30 seconds after signing the papers. Thanks for the input.

Deicide

Is there any fitment issues on the Z06 axle back due to the fact I have an A6 as well? So in your opinion, would it be better to just skip doing the head work and go with the mild cam only? Thanks for the input by the way.

old motorhead

If you're considering a supercharger, add the cam and skip the heads. You can do a cam swap now that will give you more power and still play nice with the 'charger later on (if you pick a blower friendly cam). Better yet, do it all at the same time. Cam + supercharger = crazy fun! If you do the supercharger, you'll need to pin the crank. A lot of the work to pin the crank will be done during a cam swap. You can tell wifey how much money you're saving by doing this all at the same time.

gunterwalker

I don't think there are major fitment issues. I think there might be an issue at somepoint of the install but I can't remember where. I'm sure someone will chime in. That would be a good option with you in CA.

Deicide

I have considered this route as well. The head work I might be able to save money on due to the fact I have access to a 13 CNC mills, 1 5-axis CNC mill and a 4-axis CNC mill. Also have access to a couple of CMM's as well. But likely won't do the machine work myself...that's too much like work.

Have the wifey problem in control - no wifey..all my money. So I do this now. That way when I find her I get say its a package deal.

Deicide

As I am thinking about it, it would be. Thanks for all who threw this out there. Never even considered it. With that in mind, would the ZR1 manifolds flow better than the Z06's? I imagine they might be a better option yet (if they fit) since I would guess they need to move even more CFM than the Z06.

Jim_H

The ZR1 manifolds are same as the Z06. I've got a Heads/Cam and Fast 102 LS2 with a full Z06 exhaust system and I'm making good power, I doubt headers would really give me much more.