Tom Ross

You have to take the studs out also not just the bolts just a fyi

itsShadowBlue

How's the sound level compared to headers? It's hard to tell through videos but i've noticed that the downpipes retain the tone of the original exhaust (which I prefer) whereas headers make it more raspy.

mdformula350

I didnt loosen any manifold bolts, or engine mounts, or take off any wheels.
you just need to remove 3 of the 4 studs usually leaving the top left one in i believe.
I agree i was using extensions, swivels, 1/4, 3/8, breaker bars, wrenches, etc...
once I had what worked it went buy much easier.
also i used plenty of penetrating fluid and let it sit overnight.

for sound it definitely adds loudness, yeah didnt seem to add the long tube header noise i think ur talking about.
its just louder and you can tell its going to help the flow. im happy with the results.

Bruceham

I was looking at a set of Kooks 1 7/8" LT headers with Green catted x-pipe, but the price is crazy, $2800 + $700 installation = $3500 for $35 HP gain? That's $100 per HP .
(C7 Stingray with TVS2650, Performance CAI & AWE Muffler).
These EOS cat-less down-pipes seem like the answer, since I want to keep the secondary cats with x-pipe for the smell issue.

My questions are:
- How much louder will it get? Currently, I have an AWE Touring Axel Back muffler, and it sounds perfect.
- With the primary cats gone, but the secondary cats still in place, how's the smell?
- Anyone with some hard data on the HP gains with this configuration?

9sec

when you go catless downpipes you will need O2 foulers to keep any codes from popping. as for noise any cats will dampen the sound. im completely catless and cold start up wakes the dead! once im warmed up I close the npp and cruise in comfort. I dont really have any smell short of initial startup

itsShadowBlue

Just added the EOS catless downpipes with the EOS catless xpipe. I was running just a muffler delete prior to this, and let me tell you it's at least 3x louder. I expected it to be loud but I didn't think it would be this crazy. I love it! The big negative is smell. There is a ton of fuel smell at idle so beware of that. Also definitely feel a difference in the throttle response, likely due to getting rid of all that back pressure. If you daily it, I personally think you should consider the sound level and especially the smell before going through with it.

Bruceham

Wow, thanks for the info.

Harbgrogan

They are a significantly cheaper alternative to headers with near the same performance imo.

I should have left the rear cats in place, the smell can be bad.

emfollin

If I don’t want any of the smell issues, is it better to leave the primary cat or secondary cat? It looks like with EOS products, you could do a catless downpipe or catless xpipe. Sound would be my primary goal. Short of going full catless long tubes, I doubt power gains are worth mentioning.