[djcwardog]

I just put on the Hooker Blackheart Crush Delete pipes. Sound is about the same in “Touring” mode and light throttle but a bit more raucous when I switch to “Sport” and nail it. Perfect! I know that this topic has been beat to death but I couldn’t find any direct posts. Seems like even if the car has enough flow capacity to accommodate the stock engine through the crushed sections, if you add a few mods that seek to move more air through the engine the story might become different. With these in place at least the crush areas are no longer the first, and most obvious, point of restriction in the stock exhaust. I like the stock NPP otherwise. Here are a few photos to show what came out of the car along with the first page of the kit instructions. They make another SKU for the automatic cars.

[kropscamaro16]

hope those werent too much $$$ cause they literally do nothing

[enzia35]

Yep, wasted your money.

[s346k]

i would call this a vanity upgrade.

[djcwardog]

Not sure how this qualifies as a vanity upgrade since they’re not seen at all. Just a bit more noise on the open valve and the aerospace engineer in me appreciates the potential for extra flow should I go for more serious flowrates in this 6.2 liter pump. Otherwise, my dough, my go. Thanks guys.

[whynotlikemike]

I remember my first time looking under my car and seeing them. I thought, wow some backwards chop shop slapped that on their with my Borla.... then I found out they did that factory. Still can't understand why they did it. Looks obscene haha

[LT1ornothing]

I had my non npp suitcase removed, and some nice mandrel bend pipes to replace the factory crush bends, worth every penny.

[arpad_m]

OP, as you already stated, your money, your call It certainly looks better and if it gives you peace of mind, that's all that matters.

You might want to remove the word "performance" from the thread title, though, this does absolutely nothing for performance.

[s346k]

Originally Posted by djcwardog

Not sure how this qualifies as a vanity upgrade since they’re not seen at all.

google search: vanity definition

you should add the glowtie and camaro lit door sill to the mods list in your signature, when you get around to doing them, that is.

[UnknownJinX]

Originally Posted by arpad_m

OP, as you already stated, your money, your call It certainly looks better and if it gives you peace of mind, that's all that matters.

You might want to remove the word "performance" from the thread title, though, this does absolutely nothing for performance.

OP does bring up an interesting question: we know the crushed parts don't hurt the performance on a bone stock LT1, but what about when modded?

I am assuming the ZL1 also has crushed pipes and those also don't hurt the performance, but I am guessing here.

[enzia35]

At that modded power level, most would have changed to full catback.

[Spaceme1117]

https://www.mishimoto.com/engineerin...he-crimp-myth/

TLDR:

[FoundNemo]

Originally Posted by djcwardog

I just put on the Hooker Blackheart Crush Delete pipes. Sound is about the same in “Touring” mode and light throttle but a bit more raucous when I switch to “Sport” and nail it. Perfect! I know that this topic has been beat to death but I couldn’t find any direct posts. Seems like even if the car has enough flow capacity to accommodate the stock engine through the crushed sections, if you add a few mods that seek to move more air through the engine the story might become different. With these in place at least the crush areas are no longer the first, and most obvious, point of restriction in the stock exhaust. I like the stock NPP otherwise. Here are a few photos to show what came out of the car along with the first page of the kit instructions. They make another SKU for the automatic cars.

Ignore the folks who are upset at how you spend your money. If you like it and are happy, that's all that matters. Seems like so many folks have a keyboard built for a**hole commentary only these days lol.

Regarding the flow, no it does not make more power per se by replacing the crimped section but it ABSOLUTELY affects the sound quality. There was a write up about the SS I read (will have to dig for it) and the GM engineer noted that there was no negative impact to performance for the crushed section since its actually ovoid in shape almost with similar flow capability. However, the sound quality was "impacted" certainly with the crushed area per the engineer.

The muffler itself has inlets that neck down to 2.1" on each side when you look inside the inlets after the pipe (have to cut to see it), despite the inlet pipes being larger going to the muffler itself. I know this because I cut the muffler off of mine when I made muffler deletes using the OEM tips. I measured it with a caliper on each side and it was TINY. Mine is a ZL1 but it would be the same on yours. The muffler flows decently well anyways as its straight through when the flapper is open, but you're still limited by the pipe diameter and the flapper mechanism sitting in the exhaust pipes that has to engage rapidly when you hit a certain throttle position and obviously takes up a bit of space.

Exhaust gas flow has cooled a lot by the time it hits the muffler so I dont think on a SS it will make a ton of power, but I absolutely noticed a very nice gain in responsiveness and "pep" as well as sound quality when I removed the crushed area on mine and the suitcase and ran 3" pipes with resonators out the back. Might be less noticeable on a SS but I wouldnt be surprised if you felt a bit of a boost with the crushed pipes and muffler gone. The computer targets a set torque value so without a tune you may not see or keep real gains, but again you will notice the throttle response I promise.

There was a post around here somewhere from a reputable tuner in the ZL1 forums noting that cars with a true 2.75" + swapped axle-back on modified cars consistently showed the highest dyno numbers assuming all parts being equal, vs the OEM suitcase equipped cars. Not sure where the post was, and I doubt gains were huge at all, but 2.1" is pretty damn small for a V8 even if its at the end of the exhaust so it would make sense. See the red box area in the pic attached.

Shameless plug that I am selling those deletes and they are posted up in the classifieds if you are looking for a rear axleback affordably. They are true 3" pipes, Total flow 5" race mufflers welded up, OEM tips and ProCryo cermaic coating in black (similar to Jet Hot). This would eliminate the last of the rear small pipe sections. I went with Corsa to have a quieter note after other exhaust mods, but it sounded fabulous on stock cats/x pipe.

Good luck sir either way! Link to the axleback: https://www.camaro6.com/forums/showthread.php?t=594199

[Ventmaster]

+1 Dog! After 40yrs. as a reg. respiratory therapist I couldn't sleep at night knowing that restriction was dwelling in backend of the exhaust. Yes I realized it did not interfere with flow but... visually it bothered me. Like you I could hear a difference in the sound after I deleted it. Then I added a GM performance cai (OK- that may be vanity but does require a re-flash), a Velossa ram air intake, and the 95mm TB with a MSD IM thrown in for good measure.

Finished it off with a Borla 60606 X-pipe (2nd cat delete) which a few of us talked Dave Borla into producing to get an inexpensive option to modifying the NPP exhaust. He made good on his word but the EPA shut that option down pretty quickly. Luckily I grabbed one straight away. I think the resulting exhaust sounds great and retains a good deal of the original options.

But it bothers me when this site known for its friendly knowledge based responses comes off sounding critical and self-righteous. Come on guys- all of us throw away $ on these cars. That's half the fun (the other half is driving well above the limit or wrenching on something we'd never touched before you-tube!). Have fun out there!