| 2007 Gmc Yukon front End
With new technology and new trucks come new problems to work around when trying to add more power. For example, take the new '07 Tahoes from GMC; some of these SUVs come with active fuel management to cut down on how much fuel these hefty trucks drink. The AFM system deactivates four of the eight cylinders while cruising, effectively cutting the fuel load in half. While this is great for saving money on gas, it does bad things to the exhaust note. What was a nice V-8 growl turns into something that sounds more like a clapped-out fishing boat. We are not going to sit here and tell you a four-cylinder can't sound good because they can, but this truck is only a four-cylinder during cruising. So, you get this muffled burble, instead of anything that sounds high-performance, which GM hides by keeping the exhaust very quiet.
| 2007 Gmc Yukon headers
So, what happens when you add a high-performance exhaust system to squeeze out more ponies? Well, if you buy substandard parts, you end up just amplifying that nasty burble. Luckily for all of you power-hungry truckers, JBA Exhaust Company builds a full exhaust system that not only adds 14.5 hp, but it also keeps that burble under control. Mark Matthews from JBA says, "This AFM feature was something we tuned our products for to avoid an unpleasant exhaust drone when in four-cylinder mode. Once installed, the new headers and exhaust system were tested extensively on the dyno and in real-world road conditions to ensure the operation of the AFM was not affected."
| 2007 Gmc Yukon exhaust
The Cat4ward headers and stainless steel exhaust system are available for '99-'07 Chevy and GMC 4.8-, 5.3-, and 6.0L V-8-equipped trucks and SUVs. The headers feature all of the good things you want to hear from a set of pipes, thick CNC laser-cut flanges, mandrel bends, and stainless steel. To top that off, you also get a limited lifetime warranty. The muffler and tailpipe assembly share some of the same features, such as mandrel bends and stainless construction, but also come with a straight-through-designed muffler and a 3-1/2-inch chrome-plated stainless tip with rolled lip. You might be asking why JBA chromed a stainless tip: Stainless has a tendency to turn yellow, and the chrome prevents that from happening.
To complement this system, JBA also offers a set of the company's PowerCables, which feature less resistance than the factory wires for more spark energy, and 8mm jackets for higher temperature resistance. Because these wires are made by the same company that makes the headers, they have all the proper ends to fit the new pipes. The parts are designed to be installed at home with minimal tools needed, so don't be afraid to tackle the job yourself. But, if you are not confident in your abilities, a professional shop shouldn't charge you too much to put them in.
| 2007 Gmc Yukon wd 40
Part One: The TeardownNow that you know about the parts, let us give you some advice on tear-down and installation. JBA supplies great directions with its products, so the following information is just a highlight of some key points. You won't need a lift to do this job because the headers load from the top. But, you will be under the truck a lot, so a lift would be nice-a jack and jackstands will be sufficient. Before you grab a tool from the toolbox, grab some penetrating fluid like WD-40 and spray all the fasteners and hangers.
Side-By-SideOnce the stock system was removed from the Yukon, we laid it out next to the new JBA system. Here's how they matched up:
Part Two: The InstallNow for the installation of the new parts. As stated earlier in the story, both the left and right header feed in from the top. Be careful when you are sliding these into place, because one wrong move will break off a spark plug. You could remove them just to be safe, but as long as you are careful there is no need.
The Final WordAfter everything was installed, the truck was strapped to a chassis dyno to see how much power the Yukon has now. As you can see by the numbers to the right, the installation of the JBA parts added 14.5 hp and 17 lb-ft to the peak numbers. Look at the numbers below 3,500 rpm; the JBA stuff really added some low-end grunt right in the sweet spot.
Read It And Weep! RPM HP BEFORE HP AFTER TQ BEFORE TQ AFTER 2461 44.8 100.1 96 214 2552 56.2 117.0 116 241 2643 68.5 130.2 136 259 2734 79.2 139.6 152 268 2825 91.1 148.1 169 275 2916 104.2 154.8 188 279 3007 118.6 161.5 207 282 3099 132.8 167.4 225 284 3190 145.4 172.5 239 284 3281 156.5 178.3 251 285 3372 167.3 182.2 261 284 3463 175.6 186.1 266 282 3554 180.6 191.9 267 284 3645 186.7 198.5 269 286 3737 191.4 208.4 269 293 3828 196.2 219.1 269 301 3919 201.2 225.6 270 302 4010 209.6 232.9 275 305 4101 217.8 236.8 279 303 4192 229.1 241.6 287 303 4283 234.6 245.9 288 301 4374 238.5 250.1 286 300 4466 241.2 253.8 284 299 4557 246.9 256.3 285 295 4648 249.2 258.2 282 292 4739 248.6 261.3 276 290 4830 249.9 262.2 272 285 4921 251.6 265.3 269 283 5012 254.5 267.9 267 281 5104 249.2 268.2 256 276 5195 247.8 269.0 251 272 5286 243.9 267.2 242 266 5377 241.1 263.4 235 257 5468 239.5 263.1 230 253 5559 238.1 260.5 225 246 5650 237.2 256.1 220 238 5741 235.0 252.9 215 231 5833 233.7 254.1 210 229
