Ok excuse the lack of correct terms here, but I know what I wanna ask, but not really sure how to phrase it

I have a 4-2-1 manifold with a 3inch end pipe, now the exhaust I have on the car at the mo has a 2" system so obviously it's not gonna marry upto the manifold, now i'd quite like to fit a side exit pipe, I was thinking along the lines of a 3" pipe into a central silencer/collector, with a twin outlet of 2" routed to just infront of each rear wheel, and having a small end can with a slash cut oval.

Now If I fitted something like that, would a twin system like that have a similar back pressure to a single 3" system, and also as it's a track car I need to keep it fairly quiet, so would a system like that with a central silence and two smaller ones keep the db's down while not effeting the power (I understand the exhaust isn't as important as the header when it comes to power output, as long as it dosen't cause to much restriction in flow) thats my main worry is this design to restrictive?