I came down to these to headers but dont know wich one to go with.
Any experiences with these two? MELROSE 1 3/4 Mild steel coated with 2 3/4 cats or KOOKS Stainless Steel 1 3/4 with 2 1/2 cats.
pros and cons?

 

I do not know anything about Melrose - but Kooks ... See my post below:
http://forums.corvetteforum.com/show....php?t=1682556

For my money, Kooks with a tune all the way.

 

Kooks

 

Kooks purely to get the 300 series Stainless Steel. They will last longer as they will not flake or rust.

 

Given those two choices I'd go with the 304 Stainless.

 

It's according what you are actually looking for. I have the Melrose and don't regret my choice. Nice jet coat and perfect fit. I have the 1 7/8" for the C6 Z06. H/C package in the future. Have you done a search on Melrose Headers?

 

I got Kooks for 4 reasons.

1. Shop I had installing likes them the best. Says they are easiest to get in.

2. I heard them in person with the same axle back I have and loved it.

3. I got a great price on them.

4. A lot of people seem to recoment them

 

I've put on over 200 sets of Melrose and never had a cracked fitting or split pipe, I've seen Several top name stainless systems have leak issues. Compare the flanges where the header mounts to the head.

 

It's going to be Your choice at the end!

 

I agree, I have never had a problem with Melrose products or for that matter any mild steel header. However I have had several sets of 300 series SS that has cracked at the flanges or at the collectors. One main reason is that 304 SS isn't the choice of SS for exhaust systems. The reason is that the 304 alloy hardens with continuous heat and cooling cycles and will become brittle. A better choice of alloy is the 409 alloy which isn't near as pretty but lasts.

Either way you go, it won't really matter Kooks or Melrose has excellent warranty programs so if you have issues both companies will take care of you. And either header will produce similar power gains as well.

 

ARH!!

 

Have the Melrose. Look great, great perfromance.

 

I love my 1-3/4" Mels.

 

I though about the Step Headers from Brethless Performance but dont want to deal with a muffler shop welding and s***.


ok, im going to go with........

 

We primarily use Kooks because of their proven results. With our constant testing they produce more average hp and toque then any other brand.

 

How much more? From brand to brand I see maybe 5 to 7 tops, and you can have that much differential between ambient conditions from day to day, the way the car is strapped down and other factors.

 

The difference is there whether it's a claimed 3 rwhp or a 7 rwhp difference. We've done back to back testing with several headers on the same car on the same day.

Also you'll see differences in power from the way you strap the car down if you go out of your way to make it that different than the way you strapped it down for the previous pulls. We try to be consistent with all the variables because we too like good data for our own comparisons.

Also it's not like we haven't done 10, 50, 100+ header installs all with tuning. We've used all the brands and on average the Kooks headers have given us the best results when you go back and compare. If "Joey's Custom headers"(not a real company) gave us the best results time and time again, then we would use that. We don't care who or what they are made out of as long as they do their job the best.

If you have any questions just shoot me a PM.

Max

 

Tom, I've thought about this one because we have used a lot of 300 series stainlesses at work over the years. This material does not heat treat, but it does work harden. I'm betting that the material work hardens when bent where it attaches to the flanges. Also, if they don't use a weldable grade of 300, then they can get cracks in the welds. The stabilized (or low carbon) grades are the best for welding (304L, 316L, 321 or 347).

As far as 400 series, it is not as "stainless" as 300 series. It will corrode or rust over time. The 300 series will look good longer.

I'm betting that the cracks at the flanges are most likely caused by using non-stabilized grades of 300 series stainless steel. Now, the million dollar question, what are the header manufacturers using ???

I'm going to check with one of our metallurgist at work about the heat cycles. I'm wondering that maybe the heat cycles with their expansion and contractions causes the material to work harden over time? That's the other thing about 300 series, it has a very high coefficient of thermal expansion which could make the heat cycles affect it more. However, on a good note, it also has a very low thermal conductivity which helps reduce the heat in the engine compartment.

I'm hoping that LG (Borla) uses 304L and that my headers will not crack over time. However, as usual, your information is right on. I've always appreciated your intelligence and knowledge.

 

KOOKS

 

Hi Glen, I spent over 20 years in the process industry (pulp and paper) as a EE specializing in process controls. We used a lot of 304 and 316 SS tubing for instrumentation impulse lines. In those industries if the tubing is not secured properly or made up properly to account for expansion and contraction of piping runs. The tubing will work harden as you mentioned and in time will just snap off. This can be especially dangerous in a boiler application where we are measuring high pressure steam line pressures. Imagine a 18" steam pipe that is carrying superheated steam at 1800+ PSI and the pressure transmitter impulse tube snaps off Superheated steam is especially dangerous under high pressure because it is essentially a superheated gas, it can cause serious burns in a split second, and legends from old mill hands will tell you that in some rare and extreme cases a blown steam line like that can literally cut you in half!

The headers that I have had to be replaced were made by Borla, and in these cases they were all LS1 based truck engines. I won't even recommend them to anyone these days. I had to replace 4 sets of them in the last two years. And being the good guy I am I ate the labor just to keep the customer happy. I have had to repair a couple of no name LS1 SS headers in the last year that were brought in to me with cracked tubing right at the flanges. And I had to repair a set of 8.1L SS headers from a suburban. I got a guy that is an excellent TIG welder so far so good