We've reached the end of our testing using the stock twin-turbo setup. In our quest to extract more reliable horsepower from this setup we turned to Turbonetics, which offers a variety of go-fast products including air-to-air and air-to-water Spearco cored intercoolers, blow-off valves, wastegates, high-performance radiators, turbo kits and an assortment of custom turbochargers. This month, we decided to end our stock twin-turbo setup testing with a little custom tuning and Turbonetics' new intercooler kit for MKIV Supras.

The Turbonetics front-mount intercooler kit is a bolt-on replacement for the factory side-mount intercooler. The kit includes powder-coated piping, brackets and boots. The only things missing in our box were a few more boots and an instructions manual, but fortunately it wasn't a complicated installation. The turbo-to-intercooler pipe comes with a flanged opening for a blow-off valve. Unless you've got an upgraded blow-off valve that will fit this, the opening will need to be blocked off.

Because a few months have passed since the Supra's last dyno runs, we visited evosport again for a new baseline run. Down a few ponies, the Supra's new baseline was just under 347 whp at 16 psi. Immediately, the car was unstrapped and taken to Under Pressure Fabrication and Distribution for installation of the intercooler kit. At UPFD, Supra technician Mike Calicchio performed the work and got us under way in a few short hours with a clean install.

There are a couple of things we really like about the Turbonetics kit. First off was the fitment. The piping fits perfectly all the way up to the throttle body. "You won't believe how many intercooler kits I've installed that never fit right; but this one seems to fit just fine," says Calicchio. Also nice is that the intercooler fits without having to relocate the coolant reservoir tank, which, according to Calicchio, is also unusual.

Second, the core is a decent size. It measures 3.5-inches thick, 10.5-inches tall and 28-inches wide, flows over 1000cfm, and is conservatively rated for 700 hp. "We have used that same core on a 1000-hp application," Turbonetics' Johnny Wang reports. "The pressure drop was about 0.5 to 0.7 psi and efficiency was around 80 percent."

With the car buttoned up we returned to evosport for some more dyno runs and a bit of tuning. After making sure the intake, oil and water temps were near to our baseline numbers we let her rip a third gear run through redline on the stock twin-turbo setup. With a pressure drop of 1 psi, the intercooler kit upped the power to 359 whp at what was now 15 psi. When the turbos were cranked up a little more to compensate for the pressure drop, power jumped up to 374 whp at 16 psi. All of these runs were accomplished with an air/fuel ratio of 11.7:1, as controlled by the AEM EMS.