I'm struggling to hold 19psi of boost which usually tails off around 4500rpm, I can get boost spikes of 24psi.

 

At the moment I have a 2.5inch twin exhaust with crappy gaskets which don't fit properly and probably reduce bore size it has also been somewhat squashed from my low ride height.

I have since raised the ride a touch and before forking out £1000 for a custom fabricated 3inch exhaust (which they can neatly tuck under the car to avoid being squashed) I want to know if it's going to be beneficial or a waste of money, either way it still needs changing.

I want to know if it will effect the way the turbos are losing pressure and if I can squeeZe a few more horses out when it's remapped.

 

Managed a 12.6sec 1/4mile few years back

Currently 470bhp

Gt25r turbos

Godspeed intercoolers

Q45maf

Forged engine rebuild

Shit exhaust

Loads of other stuff I can't remember

 

It's difficult to get a proper seal between the Wastegate discharge and the turbine discharge portions in the exhaust by all accounts, so you literally do have an exhaust leak. Plus with you using yours on track days etc I bet it wouldn't pass flyby Db limits and would cause you hassel.

It's difficult to get a proper seal between the Wastegate discharge and the turbine discharge portions in the exhaust by all accounts, so you literally do have an exhaust leak. Plus with you using yours on track days etc I bet it wouldn't pass flyby Db limits and would cause you hassel.

 

Yeah you're right it wouldn't pass on drive by sound test. At the mo it doesn't even pass on the stationary test but they let me do a fly by test anyway and it's ok.

 

So, how much should I be paying for a turbo back system? And how Much from downpipes back?

It's difficult to get a proper seal between the Wastegate discharge and the turbine discharge portions in the exhaust by all accounts, so you literally do have an exhaust leak. Plus with you using yours on track days etc I bet it wouldn't pass flyby Db limits and would cause you hassel.

 

Yeah there's your exhaust leak!

Yeah the divorced down pipes have a little I shaped divider in them that slots into there to seperate them. The seal isn't 100%.

Yeah the divorced down pipes have a little I shaped divider in them that slots into there to seperate them. The seal isn't 100%.

 

Yes I remember mine having these. They Don't screw in very well.

3 inch for GT25R's will help but not a lot.

 

These turbos are only marginally larger then standard turbos and too small to boost a (consistent) 20+ psi at higher revs.

You can try to adjust the wastegate actuator arms to have it hold a little bit more, but the actuator of RH turbo will be near impossible to adjust with the engine in the car.

Also ideally you will need to adjust the actuators to open at more or less the same amount of pressure.

 

A (true) dual intake, with a pair of good flowing airfilters should help get you a bit more power out of these turbos.