There’s nothing better to compliment your turbo than a free flow, mandrel bent exhaust (well, maybe an intercooler, but I already got one :P). A free flowing exhaust reduces back pressure and lets your turbo spool up a couple hundred RPMs sooner. Depending on how you make it, you can also cut some weight off of your car because factory exhaust systems are usually god-aweful heavy. I jacked up the front of the car and put it on jackstands to get some clearance so I could go under and measure. Because of the way the driveway is laid out, I didn’t need to put the rear end up on jackstands because the slight slope gave me ample space to work with. The entire system was made from one and a half 2.5” mandrel bends bought online (the other half was used in the downpipe) and part of a 10′ long 2.5” straight pipe I picked up at a local muffler shop.
Here’s the downpipe tacked together with some small sections from the mandrel bends to make the gentle curves so it snakes between the car’s steering shaft and the transmission. The top part is from the factory downpipe portion that came with the “kit” I purchased. I was told it was 2.25” but it’s just about the exact same size as the 2.5” piping, so no complaints there. This was done by cutting and tacking small sections of piping until the bends fit nicely so the downpipe wouldn’t hit any of the surroundings. This was pretty tough because I had to keep mounting and unmounting the turbo and manifold to take the downpipe off so I could weld it up (bad design, I know) and this along doubled the time it took to make the dp. I didn’t want to weld underneath the car, there’s something about laying on my back and welding about a foot above me that just doesn’t seem too appealing. However, once the bends were done, the rest was fairly easy. I left the stock cat-back exhaust on so I could see how far I had to extend the straightpipe so that it’ll reach the cat. I welded a 2.5” 3-bolt flange (purchased online along with the mandrel bends) onto the end of the straightpipe so I could continue the rest of the exhaust from there. A note on the flanges – they are really large and clearance between the driveshaft and the body of the car will be pretty tight. What I did was grind down the corners of the flange down to the holes for the bolts.