Is tHat A rEal sKylinE

Hey there, I have an sr20 in my s14 that my pops and I built like 10 years ago, and then i moved out but left it there in the garage and it sat around for years after we finished it and drove it for a while and now we're currently rebuilding it and getting it running really good again. But i'm looking at upgrading turbos. The engine currently has CP pistons, rods, bearings, solid lift tomei 270 cams, greddy intake manifold, greddy FMIC, 650cc injectors, walbro 255, and now a power labs EFR series T4 twin scroll top mount manifold.

I understand there may be some other bottlenecks in my setup such as injector size or fuel pump... I'm currently sitting right at 400hp to the wheels on a dyno dynamics dynamometer at 21psi and pump gas but the current turbo is running out of breath. I'd like to keep it under 500hp for right now to keep hooked up (i also have a audio system in the trunk weighing it down in the rear) and with the best boost response possible. But if i need to upgrade any components other than turbo to reach 475ishhp then I would like to know what those may be and possibly go ahead and get them and leave a little headroom to turn it up more if i want.

I'm going to get an EFR turbo with the SX-E housing, but I want to try to match the exact turbo for my needs. This car is a street car only. She's my baby and I don't put it on the track. Mainly looking at the EFR 7163 twin scroll and doing the SX-E housing upgrade.

Tell me what you think about that turbo in my setup. where can I expect to be? Do i need to upgrade anything else?

Thanks in advance.