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headers all the way. the sound alone is worth it. 100% retain the NPP as the option of flipping into tour mode is great if you spot a cop, or for your neighbors.
also depends what your end goal is for the car. maybe just bolt ons then catless down pipes are ok. however if you plan on doing cam, heads etc. then go with headers.
my 2 cents
I have made 640 rwhp with down pipes and cat delete . Car runs 10.0 @136 mph with no flex fuel & no meth . Like those people in the know responded if youre making less than 800RWHP headers are not worth it . I’ve easily beating C7s with headers and similar mods . As far as sound , sound is a component of heat energy . My car is loud AF ! And like many others have reported the stock manifolds combined with down pipes flow really really well. Time slips dont lie ( and it won last year index class 10.0 at cadillac attack with an auto 8 speed and I also ran this with a stock trans and converter ( chris crawford tune )
I have made 640 rwhp with down pipes and cat delete . Car runs 10.0 @136 mph with no flex fuel & no meth.
That is quite impressive. What do you mean by down pipes? You eliminated all 4 cats but still run the stock exhaust manifolds and mufflers?
I assume you’re running slicks or drag radials and maybe skinny tires up front? I am able to get a similar ET on stock wheels and tires but I’m trapping 143 to 144. I’ve already lost an axle on stock setup but dread losing a diff.
Originally Posted by Evan70
I think the reason you see a lot of people say just do a blower vs LTs is cost vs benefit. Stock manifolds from C6 Z06/ZR1 on (including all C7s) is actually very good, probably flowing as good/better than shorty headers. Can you get a gain with LTs? Yes, but as mentioned, you see about 40HP from LTs AND a tune (figure at least half that gain is the tune). On the downside, LTs take more space, may rub or cause harmonics that interfere with other systems (decent number of people in C6s had issues with active handling freaking out at certain rpms with LTs), may be prone to bolts backing off causing leaks, etc. So for many, is ~20HP and the cost worth it to do LTs, especially when you could put that money towards a blower, which makes a much bigger HP gain. Also, you absolutely do NOT need LTs to make big power. I was at almost 700RWHP on my 2013 GS (with blower) on stock C6 Z06 manifolds. So in my opinon, if your goal is 650RWHP or less, I'd save the money on LTs and just do the blower.
Any fuel smell after installing headers and high flow cats on C7 ZR1
Originally Posted by Internets_Ninja
It depends. I always tell people that headers change the personality of the car. Yes, you get more power for sure and that is great. But you also get more sound, which some people do not like. While it is very manageable with the NPP exhaust, the car is simply louder in Tour and a lot louder in Sport/Track. So you pretty much lose that mild rumble you had when in Sport/Track with the stock setup. Tour is still mostly silent inside the car so it wont be as loud as Spot/Track when stock. But Sport/Track is much louder inside and outside the car. Personally, I only use Tour for my neighbors, otherwise I love how loud the car is in Sport/Track with LT's.
Second, the car will have a stronger fuel smell on cold start until the high flow cats warmup. The OEM cats to a better job of warming up quicker and negating this for the most part. It's a rather small difference, but worth noting.
Lastly, at WOT, headers are a win win win. More power, great sound. The car just sounds awesome.
So you should decide for yourself. Will you mind any of these changes? Also, it is important to get the car properly tuned ad to not buy a cheap no name header. Cheap branded headers often don't fit properly and end up rubbing or tapping against the car which will make you wish you didn't try to go cheap.
could you perhaps go into any more detail regarding the smell for example how bad is it? How long does it last until the cats warm up?
I have a C7 ZR1 I have purchased a 2 inch ARH with high flow cat and debating whether to install, the smell is my biggest concern. I’ve never been a fan of going out in the car and coming back wreaking like exhaust thanks
could you perhaps go into any more detail regarding the smell for example how bad is it? How long does it last until the cats warm up?
I have a C7 ZR1 I have purchased a 2 inch ARH with high flow cat and debating whether to install, the smell is my biggest concern. I’ve never been a fan of going out in the car and coming back wreaking like exhaust thanks
Internet Jinja nailed it all in his description, my high flow cats heat up in no time , I have a great tuner ...and that helps a lot , if my car is outside you will barely notice it . I only smell it a bit if I start it in my garage as I always let it run a bit before popping it in gear and even then its not to bad . Now some of my friends that chose to not run cats ..... thier cars smell really bad
I can assure you , it will be worth the install .....
Internet Jinja nailed it all in his description, my high flow cats heat up in no time , I have a great tuner ...and that helps a lot , if my car is outside you will barely notice it . I only smell it a bit if I start it in my garage as I always let it run a bit before popping it in gear and even then its not to bad . Now some of my friends that chose to not run cats ..... thier cars smell really bad
I can assure you , it will be worth the install .....
Dave
OK, that’s great thanks man. Really appreciate it.
Now that this thread has been resuscitated, two years later I can add an update to my original question.
I did end up getting a set of 1 7/8" LT headers at a reasonable price that was within my ROI logic. I picked up a set of EOS headers for $600 to give them a try, or return if I did not like. They turned out to be very comparable to the Billy Boat C7 LT headers, where they connect directly to the stock X pipe, so you're not forced to also buy an X pipe just for the headers. IMO the stock X pipe is fine because I wish to keep the secondary cats.
Some might think those Chinese headers are garbage, however, I had the opportunity to directly compare them to a set of USA made Dynatech C7 headers. I was surprised to see they were almost identical, in fact the exhaust flange was 1mm thicker on the EOS. The tube gauge and quality on both looked identical, and I even ran a magnet up and down the tubes to check for magnetic properties. There were none, which leads me to conclude that they are indeed made of T-304 Stainless Steel. My installer said there was no problem with the installation, no fitment or rubbing issues. They come with SS flange gaskets, X pipe donut gaskets, and generic flange bolts, but I opted for Stage-8 bolts instead. I've had them on for about a year now with no issues, and they still look like new.
On the noise issue,YES, they do make everything louder. Before the headers, I swapped out my stock muffler for the AWE Touring Axel Back Muffler. The AWE sounded sweet with the perfect noise level, now however, with the headers, to my aging ears the noise level has doubled. It is LOUD, my teenage kids say they literally jump out of the bed when I cold start the morning. I shouldn't have sold the original stock mufflers, oh well .
Last edited by Bruceham; Apr 23, 2025 at 08:34 AM.
Now that this thread has been resuscitated, two years later I can add an update to my original question.
I did end up getting a set of 1 7/8" LT headers at a reasonable price that was within my ROI logic. I picked up a set of EOS headers for $600 to give them a try, or return if I did not like. They turned out to be very comparable to the Billy Boat C7 LT headers, where they connect directly to the stock X pipe, so you're not forced to also buy an X pipe just for the headers. IMO the stock X pipe is fine because I wish to keep the secondary cats.
Some might think those Chinese headers are garbage, however, I had the opportunity to directly compare them to a set of USA made Dynatech C7 headers. I was surprised to see they were almost identical, in fact the exhaust flange was 1mm thicker on the EOS. The tube gauge and quality on both looked identical, and I even ran a magnet up and down the tubes to check for magnetic properties. There were none, which leads me to conclude that they are indeed made of T-304 Stainless Steel. My installer said there was no problem with the installation, no fitment or rubbing issues. They come with SS flange gaskets, X pipe donut gaskets, and generic flange bolts, but I opted for Stage-8 bolts instead. I've had them on for about a year now with no issues, and they still look like new.
On the noise issue,YES, they do make everything louder. Before the headers, I swapped out my stock muffler for the AWE Touring Axel Back Muffler. The AWE sounded sweet with the perfect noise level, now however, with the headers, to my aging ears the noise level has doubled. It is LOUD, my teenage kids say they literally jump out of the bed when I cold start the morning. I shouldn't have sold the original stock mufflers, oh well .
that’s great thanks for the feedback
most likely what I’m gonna do is put everything on and retain all the manifold and original exhaust so I could reinstall if I don’t like it
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