First thanks to Jefasold who took the time to answer my many questions as it was through he that I saw a 181/70 stacked. AMX1397 freely gave me his phone number and Doc his email so I could catch him when he was not on the site. If I have missed anyone it is only at this one point, you are remembered and thanked! The 178/70 that I chose is working fine and could still use some fine tuning though at this point a 1/16th of a turn of the set-screw can often be to much as I am so close.
My only disappointment is that exhaust mods don't work out as I had fully planned a system using favorite parts from cars I've owned in the past. PYPES cats for forced induction motors, a BORLA muffler, the best IMHO, no drone and they make strong low end torque, deleted resonator with an X instead of the H-pipe. Maybe still.
For anyone considering stacking who does not want the involvement in a 178/65 stack consider the 178/xx stack. Sometimes I think I could have gone with a 178/69 but then I am being speed greedy. Getting your stock pulley turned for $90. shipped is a good deal. Being able to use the stock injectors made the stack so much easier and the car feels so much more responsive because it is!
I've enjoyed my time here on the Crossfire forum while the SLK guys have been planning a picnic! Mark

 

whats the boost? Woody

 

You would like Corsa's XO style much better than a X or H pipe. Squirrel Crusher

 

I will do a datalog today and what about Corsa exhaust? I couldn't find anything about the Corsa exhaust and have a feeling it is only a cat back. I have a strong feeling for the Borla mufflers making more low end torque than others with no drone. I need to source exhaust pipes that are not $800. first. Then I need to have them hacked and the PYPES Cats welded in to start.

 

I did 2 pulls. The highest amount of boost I saw was 20.6psi, right where I had figured it would be. The timing at that amount of boost was 25*! Time for my more conservative tune. I have never seen the timing so high with my peak boost, usually around 19-20* with the 18-19psi I was getting. Now not only do I see a higher peak boost but the high boost stays for a longer amount of time. I have 1 more fill that will be using TORCO at full strength, maybe I'll save that for my first time with the 93 octane tune just to be safe there. Jerry said the 1.5* extra he gave me to use with the TORCO was good for 25-30HP!
Again after reading Boostmonkey's very minimal decrease in et with the electric cut-outs has given me hope the exhaust may have some power there afterall. Maybe the guys who have not gotten a decent increase or got .2-.3 et decrease with the electric cut-outs did not have well designed exhaust systems? I had always thought a well designed exhaust with the SC and extra boost should get better than 15whp. Time to look at the exhaust again. Finding exhaust pipes for less than $800. has been my hinderance up to now. Do I need to go custom or are there exhaust pipes out there in aluminized steel that are less than the common set at $800.? I would hate to pay $800. and then have a shop cut into them to add the PYPES cats made for forced induction cars. Then removing a section to put an X-pipe in where the 2nd set of cats would have been.
Our problem is the cars are old so no mag is going to do any testing so we have to foot the bill ourselves and hope for positive results. Personally taking that chance with $1k is not something I could do lightly. I need to pick and choose the mods I do with a lot of research which often means a lot of questions and I have thanked some of the guys who have taken the time to answer, often the same question more than once
Then at the other end we have a guy like Woody who goes to the extreme because he enjoys it and he has other rides, The SLK is it for me. So I'll be studying what to do next for 2 months until I have the cash to do it. Questions on the way

 

I've had my car on a dyno with open headers and later in the same day connected to the stock exhaust from the resonator back. The difference was 7 hp. My tune has about the same advance with 19 lbs. of boost. (25 to 26º) I use 93 octane on the street and a mixture of 100 and 93 at the track.
I'm toying with the idea of changing my exhaust but for weight savings, not power. Burns stainless is one I'm looking at.

Les

 

Les, that's an expensive way to lose weight. I would not do it. Each 100lbs. is supposed to yield .1 change in et. Will the burns system save 100lbs.? You showed what Boostmonkey saw. Little to be gained with open exhaust when compared to a good exhaust system. I believe he saw a .08 difference in et and 7HP would work out to .07et wise. More encouragement that a good exhaust system will yield some power, better than 15whp. My tune is not that far off then as at 20.6psi it had 25* of timing and that was my more aggressive tune.
Les, have you tried an 18" extension on the open headers, should increase torque but you may have to try different lengths on the dyno to find the best. I'd try that first considering what those headers cost. Mark