Increasing performance and noise with Prodrive backbox?

[Matt106]

I've recently delved into the world of turbo power in the form of an Impreza wagon. It's already had a couple of subtle modifications to increase the power but I'm hoping to unleash some more horses.

The main issue is what to do with the exhaust system which is probably restrictive. It's currently running a Prodrive backbox, Prodrive decat, decat up pipe and sports cat down pipe. The centre section is standard and I'm hoping changing this for a straight through 2.5" will increase the flow and noise?

I like the looks of the Prodrive box so fairly reluctant to splash out on 4" Jap can! Will the 2.5" system be free flowing enough to reach 330-350bhp? I already have supporting modifications to reach this power (in theory) apart from injectors.

[Matt106]

It's already got a harvey up pipe and 225 fuel pump however still need injectors, solenoid and possibly plugs.

I may swap out the centre section for an aftermarket one and see if it increases the noise. Most aftermarket system look a bit out of place on the wagon in my opinion.

I've got Thwaites, Roger Clark and Andy Carr all within easy reach so it'll no doubt be one of those guys.