Then the turbo's are not set up in compound, two of those set up in compound would not move enough air to support a stock 3.0 inline 6. You could still run them, but you can expect the car to fall on it's face around 4krpm. In parallel, yes it will provide enough air, but you will not be seeing 30psi from those turbos. You will be over the surge line at that high of a pr. & low-mid 12's tells me nothing about the setup, My n/a gt runs mid 12's on street tires with zero suspension work & stock heads, all the same my friends turbo 4 cylinder mustang runs high 10's with street tires. If you're trying to tell me that you're getting those numbers at 30psi then I'd say you have a horribly horribly built engine, but you're running 15psi unless the turbos have been modified for nearly doubling the cfm & moving the surge line over in which case you are no longer running anything close to two td03's, but on the off chance you are then you have a very horrible twin turbo kit.
You're running 15psi total (15psi per turbo = 15psi at the intake) or you lied about the turbo's you're running. That or you lied about your strip time & the dyno #'s in your sig.

Turbos will always have lag, you won't get away from that but you can downshift to get in a higher rpm & reduce lag time quite a bit. If you're worried alot about it I would recommend going with a positive displacement s/c instead.

 

No lies here, these are the stock turbos from BMW. I am not worried about lag so much as I would like for the turbos to spool up by 2000-2300rpm or so.

Thanks for your insight, and sorry for my lack on knowledge.

 

There are lots of things you can do to lower boost threshold, unfortunately if you run two smaller turbos or a small single you will get full boost by 2000-2300rpm, but you'll run out of steam at closer to 4000-4600rpm. A sequential setup would help this, but on a v8 mustang there isn't much room for plumbing that, on an inline 6 or 4 it's a bit easier because of the room available. It could be done though.

Another downside to smaller turbos is they aren't too forgiving when it comes to cam selection & heat generated at wot in higher rpm. With smaller turbos you will have to get a cam with a smaller amount of overlap, backpressure is higher with smaller turbos & if it reaches the point where there's more pressure in the exhaust manifold than the intake manifold it will shove exhaust gasses back up into your intake causing a big power loss. Larger turbos on the other hand work pretty well with most n/a cams because of less backpressure.

You can do a few things to get boost off the line, either using nitrous until the turbo spools (which i don't like due to refills) or you can setup an antilag switch to work with a chip or standalone which would work by retarding ignition timing & putting in excess fuel. The downside to this is you can't use it all the time because when on fire will be leaving the cylinder into the exhaust manifold which will spool the turbo up at idle & cause things to get hot very fast, it's not that bad if you only do it for a couple seconds, enough to spool the turbo then take off. Another option is to look into split scroll exhaust housings & making a header for them to give you a broader powerband, but even with that it's not going to give you insanely low boost threshold #'s. Then there's the vgt turbos which are quite common on diesels, but not gasoline engines. If you have money you could go that route, the ones built for diesels aren't very forgiving though due to being built to run at a much lower operating temp than gasoline engines. Holset has made some that have fixed vanes & uses a titanium wheel which may work, but I haven't heard of anyone putting one on a gasoline engine, they are pwm controlled as opposed to vacuum. If you have the money to invest in one, one could be built to withstand the temps that a gasoline engine puts out & they offer a very low boost threshold with amazing high end power.