I'm wondering about dual vs single wastegate. Supposedly dual wastegate on a divided housing and flange is better for spool? But I really dont see why that would be. I mean the runners that connect the 2 pipes would probally be long enough so that the exhaust energy wouldn't really transfer between pipes, at least I think. I also know that it allows you to use smaller waste gates. Is there really a difference between the two if the exhaust manifold stays the same? Is two small wastegates cheaper/more/same than 1 big? I'd love to hear opinions and experiences with this.

 

There's a lot of nuance to WG tuning/placement/selection.
If 2 the WGs flow more than the 1 larger one, then that's better... kinda.. There's a lot of questions to ask.
What do you have room for?
Is the manifold divided?
Are the WGs in an orientation to have priority?
What size is/are the gate(s)?
What is the spring rate?
Will the gate(s) be recirculated or open?
How is boost control being tuned?

Dual gates in general tend to be a little more responsive and tunable, but a lot of that comes down to the controller and spring rates. BUUUUUUT.. if those dual gates are not positioned correctly, or plumbed poorly, then a well set-up single will out class them. (just my .02)

My REW has dual Turbosmart 40s, on a 3 port valve, 7lb springs, controlled with my Haltech. I have near infinite tunability from ~6lb to 16lbs. I chose to dump them to atmosphere for the sake of plumbing.

 

What size is your turbo? i was thinking of running 7lb and using a 3 port to raise it if needed.

 

Borg 366. Ive got the 7's in it now for pump gas cruising and DGRR. When I return, I will probably swap them for 10-12lbs to start making E85 pulls.

 

You don't need much area to dissipate pulse energy, the good single manifolds run a divider right up to the valve face.

generally speaking, if trying to get a wide control range with a single 3 port reference valve and conventional boost control strategy, the smaller gates used as twins will allow a higher boost ratio than larger gates as the diaphragm & spring have relatively larger area compared to the valve than most of the 60mm stuff. If running a BOV you have more flexibility if trying to limit power for traction or inexperienced drivers if you don't want to run a hard boost cut if you are willing to add another reference switching valve for a low power mode with intake side bleed.