z28bryan

iTrader: (7)

I am going to pick up some Kooks long tubes with a catted ypipe for my 1999 z28.

There seems to be a few selections of header sizes:
1 3/4" x 3" - Stainless Pair
1 3/4" x 1 7/8" x 3" - Stainless Pair 0
1 3/4" x 1 7/8" x 3 1/2" - Stainless Pair
1 7/8" x 3" - Stainless Pair
1 7/8" x 2" x 3 1/2" - Stainless

Now for some stupid questions I am assuming that the last number (3" or 3 1/2") is the connection to the Ypipe. Since the only catted Y they offer is 3 inch then I'm guessing it narrows down my choices to:
1 3/4" x 3" - Stainless Pair
1 3/4" x 1 7/8" x 3" - Stainless Pair
1 7/8" x 3" - Stainless Pair

Given LS6 heads and a Corsa Catback exhaust, which ones of these will fit on my car? What is the difference between the 1 3/4 and the 1 3/4 x 1 7/8? Does this mean the pipe size increases a little further down the tubes? I couldn't find much of an explaination for these anywhere

NLinnear

iTrader: (8)

The 1 3/4 headers would be just fine. The 1 3/4 X 1 7/8 are stepped headers. They increase in size along the primaries to increase flow. You would not benefit from them with how your car is setup right now.

Let me know when your ready to buy

Gold Phoenix

iTrader: (1)

While we are on the same subject. What do you guys think of the 1-7/8"-2" stepped headers for a high ouput FI setup?

z28bryan

iTrader: (7)

Well mod plans are going to be a cam similar to the TR 224 and LS6 heads actually. Right now my internal engine is all stock but that is going to change.

NLinnear

iTrader: (8)

Gold Phoenix, what is your definition of "high output"?

Bryan, with the mods you are listing, you'll be fine with the 1 3/4 headers.

Gold Phoenix

iTrader: (1)

Over 800whp

black01_WS6

iTrader: (13)

If you are using a 402 and going FI in the future get the 1 7/8's you may not benifit that much right now, but you will need them in that set up. The way I look at it do it once and do it right. also look into the qtp's if you go 1 3/4's as they are including the merge collector for free with those.

Gold Phoenix

iTrader: (1)

Actually, I have the F1R kit and I am building the 402. I am still toying around about the exhaust and intake systems.

black01_WS6

iTrader: (13)

with what you have in mind I would get the 1 7/8. as for intake get the fast intake and the nick williams throttle body as the fast 90 throttle body sucks.

NLinnear

iTrader: (8)

Agreed