Before and after 3" exhaust

[f00g00]

Hi,
The first run is with a stock exhaust with a hollowed out cat at 14 psi. As you can see the twins got all choked up and the HP dropped when it got to full boost and lost allmost 60 HP. I could really feel the drop as it stopped pulling on the road. AFR's were allways below 11 at full boost.

Mods:
rebuilt twins with steel wheels
MBC
fuel cut defencer
speed cut defencer
Stock ECU

After 3" exhaust (chinas best from DM) the run was quite different. I can feel it pull all the way till I let off the gas but I had to turn down the boost to 12. If I go higher it sputters and pops because the stock injectors can't keep up with the fast spool and free flowing exhaust. I also did the run 2 months later on a different dyno jet where thay also checked torque and it was a little higher at 308 tq vs 305 hp.
Next mod is a new harness from dr tweak and with 550's and resistor pack and hopefully can crank up the boost a tad more and get past 350 hp at the wheels.
Bottom line is I can't believe how bad the stock exhaust really inhibits performance

 

[kotu100]

Wow that's insane. 40hp gain just from exhaust is rediculous.

 

[f00g00]

Around 100 more at max without
the choke factor.

 

[#04]

stock intercooler?

 

[te72]

I didn't see engine mentioned, but I'm going to guess 1j given the posts and power level. Never did understand dynos that measure in MPH though, that really doesn't give you much reference as to power level vs rpm.

Have you replaced the y-pipe yet? You won't need that boost controller after you do that.

 

[f00g00]

Sorry, forgot to mention its a JZA70 1J. The IC piping is 2.5 with a 24x12x3 Intercooler from Dm and the y pipe is stock.
Gas mileage is also up almost 2 mpg.