John,

Putting a step down right at the outlet of a turbo is no good by any standard. You have the internal waste gate and the 90 degree step to to further add turbulence? Would you put a smaller mismatched flange on your head? I really hope you said no to that! Larger non hybrid turbos do not have the internal wg's dumping into that flange so you do not have the added volume, hence the smaller ID outlet size. Non hybrid turbos are either 2.5 or 2.75 at that point. John stick with what you know about making power, V twin's or flat 6's it the same air pump. To further drive what I have learned.... Do you see airplanes with mismatched seams of .25 of and inch on its skin? Then ask your self why? There is your answer..

 

I am not a fan of restrictions on muffler inlets...maybe you can do a little modification at the muffler flange side

after my aftermarket headers cracked i do some homework on my oem headers ...you can see at the attachment ...and I was very surprised how good oem headers after that modification do his job....that is a indicator for me what a small restriction can do

i gain diameter at the turbo inlet side from arround 35mm to 40mm

 

I am with you on that Tim..
Thanks..

 

Looks nice , did you take those pictures of my ex.manifolds?..LOL..
Nice job,I did the same to mine..

 

hope following are the right words.....it had to be clear for me ... you already know what is to do

 

I went to a Porsche dealer yesterday and saw a new exhaust sitting there for a customer.
I saw it had a smaller diameter flange opening on the cat then the diameter of the turbo exhaust outlet..
I dont know why others dont take that little extra step to make it the same size,line up....So it doesnt have that step..lol.
Its Basic 101 blue printing...

 

 

 

when i ran alphas i had a matached reducer because the outlet on alphas is definitely bigger then 3" and a 3" pipe will fit inside the turbo. samll things help make big things work, not always on the dyno. chris green was one of the first to post about this from what i remember and he did a lot with very little. 10.2 with 700whp is super impressive.

this is how much was needed to match A3076....
for whatever its worth i got great gains from going 2.7" high flow hjs catted exhaust to 3" catless and my car was in 6-700whp range back then....

 

Nice,,Thanks Mark for your insight..

 

So did you use a flange bigger then 3" to work equally with the alphas? Or did you modify them by porting out the internals of the flange?

 

Outlet of the Alphas is larger that's is why I had the exhaust built like that. Used a piece of a 3.5-3 reducer on each side and cut as needed, but you can see how much was needed and its noticeably larger then 3".

 

Hmm...... Oddly similar..

 

John, FYI - Not only do we bump the pipe to match the turbo on all our cats and cat bypass pipes, we also port the weld...

 

What brand are those Timmy?