Back in our March '06 issue, we installed a bevy of bolt-ons to our project 2005 GTO for a 34 rear-wheel horsepower gain. Included in that story was a quality set of Stainless Works' 1.75-inch headers. Though they fit great up top, we had some trouble lining up the intermediate pipes to our factory exhaust system. This wasn't SW's fault: we'd installed a 2004 GTO-only driveshaft loop for safety's sake back when the Goat was brand-new and the loops weren't out for the '05's different exhaust system. This move would come back to haunt us later on, but for now it caused interference issues with the exhaust that would have to be fixed.Once Stainless Works was told of the problem, it offered us the opportunity to visit the shop in Chagrin Falls , Ohio , so the SW techs could verify that the problem was on our end, and offer up a solution. Not only that, but Stainless Works also offered to bolt up its brand-new 2005 GTO exhaust system as well!That was a deal too good to pass up, so I jumped onto I-80 West and headed toward Ohio . When I got there, I picked up Stainless Works' Al Noe, and we cruised over to GMR Speed in nearby Hinckley for a baseline dyno session. The plan was to baseline, swap the factory Sport Appearance Package exhaust for the Stainless Works system, and then re-dyno to see how much power we gained.
 Barely visible in this photo...  Barely visible in this photo from a past story is the GTO driveshaft loop. It caused some fitment issues--we installed this loop when the '05 was brand new, knowing that it was made for 2004 GTOs, because we wanted a loop for safe drag-radial track testing. But because it wasn't made for the '05 cars, the front pipes had to be pushed forward to get the factory exhaust flange off of the loop, which meant the entire exhaust had to come forward. It didn't line up right, so we decided to visit Stainless Works' Ohio shop to rectify the problem and install SW's new GTO exhaust system. |  Before we swapped the exhaust...  Before we swapped the exhaust out, we made a trip to GMR Speed for a baseline dyno number. Once GMR's crew strapped it down to the Dynojet, our Goat produced 356.1 horses and 356.5 ft-lbs at the wheels. |  |
 Back from the dyno, we rolled...  Back from the dyno, we rolled into the SW shop and immediately went onto a lift to start the exhaust swap. In addition to selling mail order exhaust systems, Stainless Works also installs everything it sells, as well as doing custom headers and exhaust fabrication in-house for applications where a standard exhaust system will not work (LSX engine in a '57 Chevy, for example). Stainless Works is one of the few exhaust manufacturers that still does as much as possible in-house--it has CNC mandrel bending equipment, two Trumpf CNC laser cutters, and a Trumpf CNC press brake. With 50,000 square feet under its roof, SW literally builds every component of the exhaust systems in-house, with the exception of a few smaller commodity-type items. If you are in the area, call to schedule a shop tour, as it is an impressive manufacturing facility. It is also good to know it has not jumped on the "outsource to China " bandwagon that is so prevalent today. |  The GTO's factory exhaust...  The GTO's factory exhaust sounds OK, and the SAP's different mufflers create a more aggressive tone, but we know damn well that there's power to be had by installing a brand-new system. |  Tom Long of Stainless Works...  Tom Long of Stainless Works will be doing the work on our Goat. One look from the SW staff verified that this loop was causing all of the fitment problems, so it was simply cut off. A more serious problem had developed as well--the loop was making contact with the larger BMR driveshaft. We'll get more into detail on that later, but if anyone else put on this loop with a bigger driveshaft--take it off now!!! Tom starts the exhaust swap by grabbing a 15mm socket and removing the stock mufflers--pretty simple with only the two-bolt flanges and the hangers. |