Ls1toAMG

From almost every thing I have read there are no gains here. I'm new to the forced induction community and I find it hard to believe there isn't atleast 10 rwhp for cutting out cats 1st or second. School me..got a good exuaust guy that could do it on the cheap..

HeissRod

What you need to do is replace the stock connection between the manifold and cat pipe. That is the majority of the factory bottleneck and there is a thread somewhere about it.

draggbody

the inner diameter at the collector on the stock manifold is 1.75"...

Worth the wait

Deleting primary cats can provide gains. Those gains are increased with a tune and some type of headers.
Good LT headers and a tune should yield 40-50whp. I suggest this as the first mod, and the 82mm throttle body as a second.
Pulleys are the cheaper route to power, but can lead to install issues and rely on running more boost (stress) through your engine.
LT's and TB will increase power, while lowering your boost.

Good luck!

Hulk

A bigger tb needs more air which means a bigger pulley, you won't gain much with a stock pulley and bigger tb.

Also what drag and heiss said is true the big restriction is at the stock collector if you can call it that, it's tiny, plus the manifolds are restrictive too because they have another manifold sleeve inside. If you take it apart you can see and be astonished

DVC

Not to mention the stock manifold features a 1.6" ID collector, and primaries that measure about .10" smaller than the exhaust ports in the head. Go with these instead:

romeomikehotel

I think cutting up some stock manifolds to make log-style headers would create more flow and better results for not a lot of money. After I take my stock manifolds off I'll cut them up and give it a try at least and if anything good comes of it I'll post a DIY

BagMan

I believe Shardul or Exotic Metal did this years ago. If I remember correctly, he welded on a bigger outlet to the manifold and a larger collector. There were SOME gains, but the primaries are still unbelievably small.

There's a lot of good info in this thread and some pics:
https://mbworld.org/forums/w211-amg/...ders-must.html

Edit - Here are the pics of Shardul's creation: https://mbworld.org/forums/engine-pe...manifolds.html

Hulk

Those were mine for awhile, actually on hold for a member, these made me 20/20 on dyno, and believe it or not I ran 11.1 with these. The member getting these will be happy. Took shardul a long time to make them, he said he would never do it again lol

BagMan

11.1 is impressive! What other mods at the time?

Hulk

180 pulley, smaller sc pulley , bigger tb, killer chiller, 3" exhaust

BagMan

Nice!

Let me know if the deal falls through on those. I may be interested.

I'm looking for something I can install myself and switch back to stock easily.

Hulk

Np sir

Ls1toAMG

So a larger pipe from the manifolds that delete the cats sounds like the way to go.

Hulk

You still need to gut the manifolds as there is a sleeve manifold inside

It is a time consuming job

sircl55amg

yes it is ..

sircl55amg

humm ... i need to do that !!!

Max.H

Ive been saying that for awhile too. HULK has a pair for sale at a good price. You should try them. 20 whp 20 tq is big for such a small mod.

Not to mention the substantial reduction in IATS from removal of those awful cats and tiny pee hole restriction at the collector.