Hi Guys,

Ive searched and searched and keep getting different information! My motor is getting built now and I have to make a decision on the springs for the actuators because I really don't want to have to swap them out. I will be running the APS 3.5in test pipes and the APS 2.5in dual exhaust and what to have a base boost pressure of 12-13psi but have the ability to hold 17-18psi to redline running the Haltech boost control (Yes I know that will be hard with an IWG). Hal has suggested the Yellow springs but I'm afraid the boost will taper too much in the higher revs. My power goals are around 550rwhp.

Is anyone running the same exhaust and actuator combination that can confirm?

Thanks
Matt

 

With the 3.5" pipes you have very little back pressure. I have JWT turbos but I use those same down pipes and run 9 psi springs and have no trouble hitting 16 psi. I doubt I'll have trouble at 18 or 19 either... I doubt you'll need 12 psi springs to hold just 18 psi. Usually you can double spring pressure, but with those 3.5" pipes you may be able to do better.

 

Thanks. Ill give the yellow a go then.

 

I would use the blue. For whatever reason, we aren't seeing the claimed base boost pressures that forge claims we should see. Even with the red spring, we are only seeing about 15psi base boost pressure with the APS TT kits, and 3.5 inch downpipes/3inch exhaust.

 

I have the 3.5" into 2.5" exhaust.

I am running red springs. My base boost is around 12 psi....

Now my buddy is running the same exhaust setup on his G and running the blue. Not sure what his base boost is, but 17-18 psi is no problem.

In short, get at least the blue springs.

 

I personally would do the red springs. On a setup with 3.5 downpipes and 2.75 exhaust it makes around 12 to 13 base. With a 3.5 inch exhaust it barely makes a little more. With proper tuning, everything should be fine. Good luck.

 

I have the red springs on my APS TT. With standard test pipes and the 2.5 TD APS exhaust, my base pressure is around 14psi. I have no problems ramping it up to 19+psi. My only concerns right now is that the boost drops down to spring pressure up top above 5000rpm. That's with a UTEC.

 

I HAD the yellow springs when I did my built with 3.5in DPs and Greddy evo TT exhaust. I could only get 7psi spring pressure and 12psi maxing out my Greddy Profec S boost controller. I switched to red springs on Sharifs recommendation and my spring pressure boost is now 14psi and I can turn it up to 20psi without a problem (although it's useless with my stock cams and plenum).