The kit installed easily, and we observed no interference between the piping and any part of the motor -- this is important because hard metal piping can make a lot of noise if it contacts anything else metal. The stock piping has many segments, and at least three different pipe diameters, plus a convoluted section that looks to be designed to reduce noise. The Cobb piping is all smooth and the same uniform diameter throughout, and the number of joints is kept to a minimum.
It looks very nice, with black sand-finish powder coated aluminum piping, but enjoy it while you're installing it, because once it's on the car you'll never see it again. Does it add power? We don't know for sure -- we have not re-dyno'ed the car since adding the pipe kit. But just look at the differences in the plumbing. How could it not flow better? Don't worry, we'll have the car back on the dyno at some point, so this power question will not remain un-answered.
We also got in a set of lovely bronze Rota Grid wheels, in 18x9.5" size, +38 offset. When we first looked at the wheels they looked colossally wide compared to the stock 19x8" Focus RS wheels. We had our doubts as to whether they'd even fit under the car's skinny fenders. There's also the question of the Focus's giant Brembo brake package up front. Those wheels are awfully dishy. Would they clear the brake calipers? Well, yes, they do. They even fit under the fenders. Mostly.
For tires with went with a Continental Extreme Contact Sport in size 255/40R18. This is about 2% taller than stock, about as much as we'd suggest deviating from the stock tire size. We also considered going with a 255/35R18, which would have given us more fender clearance, but that would have been 2% shorter than stock. The taller tire has a slightly taller sidewall for a tiny bit more ride comfort, which we'd be grateful for.
On first blush, the tires appeared to stick out from the car a bit. Doing our scientific experiments (otherwise known as flailing the car around an empty parking lot like a nut) regarding suspension motion and fender clearance, we established that we couldn't actually get the front fenders to run into the tires no matter what we did, but that the rear fenders would ever so slightly skim the outer sidewall at full suspension travel. It was not enough to cut the rubber up, but the sidewalls got a little polished. A 255/35R18 or a 245/40R18 should fit fine without any clearance problems. If we had any camber adjustability, we could also tip the tops of the tires in slightly to get them to tuck under the fenders, but for now our suspension is 100% stock.
We got a ton of positive comments regarding the look of the car with this wheel and tire setup. The deep concave shape of the wheels is a sharp contrast to the very flat OEM wheels, and the much wider tires and track width give the car a very chunky and solid appearance.
We've already been observing that the car picks up and throws a lot of rocks and gravel, and with the wider tire package we're even more concerned about blasting the beautiful Nitrous Blue paint with road debris, so we may end up installing some Rally Armor mud flaps to minimize the sandblast threat.
Parts mentioned in this post:Cobb Tuning hard pipe kit for Focus RS, Rota Grid 18x9.5 +38 , Rally Armor mud flaps.