A new part brought to you by..... you! Over the last few years our Equal Length Header has been one of our most popular and most loved parts we have made. From the beginning we choose a perfect size tube for the primaries which produced more power and quicker turbo response compared to any other header out there. This was proven first by us, then by customers on forums and other shops.
Even though its been a huge success for us, we still had customers that asked us for a bigger header. They thought that our header was "Too Small" and would restrict HP. Even with our proof of the header increasing spool and HP on cars making 400+ WHP, customers still asked for a bigger diameter header.
I said FINE, here is your damn header! :)
So below is the testing we did using my 08 STI in one of its many states of tune. The test was done from one day to the next and with a few runs done on each header. My 08 STI at the time had our prototye EFR 7670 Rotated Turbo Kit installed along with our normal Equal Length Header (not wrapped), Cosworth ECU, FMIC, catback ,our PWI -2 Water/Meth injection kit, Walbro255lph pump (properly installed) and Deatchwerks 850 Injectors. Other notables is this car has the stock TGV housings installed and working, stock heads and cams, an Exedy Twin Plate rattle box, and a built (using Cosy parts) short block.
The two runs show the best of what we saw between the two headers. The dyno numbers varied from a gain of 8-10WHP across the board. Keep in mind the Blue Line is our normal header (not the stock header) and the Yellow Line is the prototype header with larger primaries. Both were run at 1.7 bar of boost or 25psi. On this turbo, 25psi nets 460 Wheel HP and having dynoed this setup a few times before that is pretty typical.
As expected a bit of low end/off boost power lost, but some HP gain at higher HP levels. 10HP with no additional boost or tuning is pretty good and for sure those who are planning on buying a header and running close to 500WHP, should for sure consider this header over our regular one. What we didnt show is that at 20psi there is almost no HP gains or at least something I felt ok with publishing.
What is the downside of this new Bigger Header? For sure the thing not seen on the dyno is the off boost power change. This is something that is noticeable on the street, and almost completely masked by the dyno. Its hard to put a figure on how much less torquey this feels, but its noticeable but nothing that will turn customers off. If you look at this as nothing more than an RPM when the turbo reaches full boost, you will see there is no change there. For some this is all that matters. If you are even remotely concerned about the response change stick with the normal header. It still make 15WHP over the stock header and spools the turbo faster.
What I like about this is we now have broader range of customers covered with the two headers to choose from. If a guy is worried about response and may only have the stock turbo installed, then the normal version is perfect. If you are a guy that needs to eek out that extra bit of HP, then the Big TUBE header is the obvious choice. Don't say we never listen to you guys!