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Discussion Starter · #1 ·
I have an '08 6m, NPP exhaust w/ mild to wild, Z51. I bought the car new, and it has about 10.5k miles on it. I want to put some long tubes on the car, and was wondering which diameter pipes should I use? 1 3/4 or 1 5/8? Will the stock NPP be ok, or should I go with a different cat-back? I would like that nice 60's muscle car rumble:wheelchair:. Any help or opinions would be appreciated. Thanks in advance.
 

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1 3/4" for the C6. LG, PFAT, AR or Kooks all make a good set. Headers, assuming you add cats, do not add much volume. It certainly will not change the tone and sound quality much. If you don't like the NPP sound, you'll have to switch to another catback.

IMO, the LS motors don't have the cool 60's sound no matter what muffler is put on them. A lot of people think it is the firing order, but no matter what you do it won't sound as good as some other cars.
 

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Thanks for responding guys. Fish, I was mainly concerned about the difference in pipe size. About the sound, I know it's different strokes for different folks. Ragtop, I agree it may be the motor itself. The NPP sounds ok, but I guess I'm just dreaming. I had a '69 El Camino with an early 70's 350. It had a mild cam and Hookers w/flowmaster 40's. I loved that sound, but I'm sure I can't get the vette to sound like that, no matter what.
 

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Thanks for responding guys. Fish, I was mainly concerned about the difference in pipe size. About the sound, I know it's different strokes for different folks. Ragtop, I agree it may be the motor itself. The NPP sounds ok, but I guess I'm just dreaming. I had a '69 El Camino with an early 70's 350. It had a mild cam and Hookers w/flowmaster 40's. I loved that sound, but I'm sure I can't get the vette to sound like that, no matter what.
I don t think you can get that rumble of a 60-70s muscle car from yours ..the sound of my LS motor just doesn t compare with the lope from my 383 Stroker in my C3....the comment I get a lot when I pull in with my C3,somewhere, is ...How Big IS That Cam ,Anyway??? ..... but the 1 3/4 inch long tubes should benefit performance if you upgrade the rest of the system
 

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Ummm, I have 1 3/4 and I know there are 1 7/8, but I never heard of 1 5/8 for our C6's.
 

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Ummm, I have 1 3/4 and I know there are 1 7/8, but I never heard of 1 5/8 for our C6's.
I haven't seen anyone who has run the JBA's post a dyno showing any torque benefit from the smaller tubes on the JBA. The 1 3/4" LG Pros design produces very good torque gains. If the JBAs beat the LGs (ARs or Kooks), that would be all over the forums. I'd stick with 1 3/4" for normal NA builds.
 

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...and Ragtop, I was not recomending the JBA s , just answering 2vettes inquiry about their existence.. as I said earlier, the 1 3/4 in. would be my choice on OPs car
The JBAs are a good price. Just posting that in case someone was interested in more midrange torque than top end power and thought the narrower tubes would help down low.
 

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The JBAs are a good price. Just posting that in case someone was interested in more midrange torque than top end power and thought the narrower tubes would help down low.
just out of curiousity , I sent a request for any dyno comparison of the 2 primary tube sizes to JBL.. this was their Response.. "That would be a question for my tuner Josh. You would want to call him at 888-737-8388 ext 209."..I could not get thru to him..
 

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I don't have any specifics but I guarantee that the primary size affects where peak hp occurs
smaller = low end
bigger = top end
 

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check this out Power Numbers Avg. Avg. Peak Peak Combo TQ HP TQ HP LS1 Vette
Manifolds 369.7 301.2 391 @
4,900 396 @
6,100 LS1 Camaro
Manifolds 360.5 292.3 384 @
4,400 384 @
5,700 TTS 1 5/8
Headers 372.4 301.9 397 @
4,400
396 @
5,600 TTS 1 3/4
Headers 372.5 302.5 396 @
5,000 396 @
5,700 TTS 1 7/8
Headers 373.1 303.3 396 @
4,400 402 @
5,800
turns out, for stock LS motor, , peak HP 396HP for the 1 5/8 and 402HP for 1 7/8 but at higher rpm...so it would appear the 1 5/8 are not sacrificing much at the top end and are producing more at 4400rpm than 1 3/4
 

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sounds right
we used header size to tune our dirt cars for the conditions
of course we also tuned the intake too
 

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Fish, where is the data from?
 

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Fish, where is the data from?
Its from a test done by Car Craft Magazine ,, to compare 1 5/8, 1 3/4 ,1 7/8 inch primary tubes , of the same design headers ,on the same LS motor , not in the car ..... there may be other tests, , but this is what they had ..I would have thought there would be bigger difference at high end...now, a different brand header may show different results
 
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