ZL1 NPP Difference?

[Redrockit]

I just scored some cutoffs on ebay, now I'm wondering. Is there a difference between the SS and ZL1 versions? I have heard ZL might have larger or different angled tips. Anyone know? Also, should I order the 22829478 diffuser or the 22829477 diffuser for my SS? Appreciate a quick answer before these ship!

[CamaroDreams76]

Nothing. Only different NPP setup is the Z/28. SS and ZL1 setup are 2.5in piping. Z/28 is 2.75.

Difference in exhaust comes from the headers, ZL1s have steel headers where LS3s have cast iron and Z/28 are a try-y design.

[Ashen L99]

Originally Posted by CamaroDreams76

Nothing. Only different NPP setup is the Z/28. SS and ZL1 setup are 2.5in piping. Z/28 is 2.75.

Difference in exhaust comes from the headers, ZL1s have steel headers where LS3s have cast iron and Z/28 are a try-y design.

I need to get my hands on a Z/28 system because I’m wondering if when the pipe meets the muffler it doesn’t just neck down making the mufflers the same but the pipe leading to it a little bigger. Idk though Z/28 systems are hard to come by. Zl1 and SS systems are pretty common.

[CamaroDreams76]

I tend to believe its the same size all the way. Dont know from experience but just my theory from people with vettes doing the "npp mod"

[AG1LE]

Originally Posted by Ashen L99

I need to get my hands on a Z/28 system because I’m wondering if when the pipe meets the muffler it doesn’t just neck down making the mufflers the same but the pipe leading to it a little bigger. Idk though Z/28 systems are hard to come by. Zl1 and SS systems are pretty common.

There's an adapter kit from GM



https://www.hawksmotorsports.com/201...ook-up-kit-gm/

[camguynj]

So a Z/28 does NOT have 2.75” mufflers?

[Ashen L99]

Originally Posted by AG1LE

There's an adapter kit from GM



https://www.hawksmotorsports.com/201...ook-up-kit-gm/

Right, i’m talking about back at the mufflers though, I wonder if the Z 28 mufflers are like the C6 Z06 mufflers that are actually 3”.
Or in our case 2.75”