An aftermarket exhaust is a great place to start when modding any car. A complete system can add an extra 40 hp at the rear wheels with a tune. Our tech article on understanding exhaust systems is a must-read for any first-time modder. Before I get into the nitty-gritty of exhaust systems, here are some important points everyone should know about aftermarket exhausts:
- Purchase your headers and mid-pipe from the same manufacturer – some manufacturers sell products that only bolt up to their own, or OEM, exhaust components.
- Long tube headers sometimes require oxygen sensor extensions, but always require a new mid-pipe (shorty mid-pipe).
- If you choose to run an exhaust with no catalytic converters you will need to re-tune the computer to get rid of the check engine light.
IMPORTANT – Although some high-flow catalytic converters will pass state emissions testing, it is still illegal (under federal law) to run anything other than a catalyst that meets OEM specifications. You should always be aware of the state and federal emissions laws.
A lot of customers ask me about the difference between short tube and long tube headers. I think much of this confusion stems from the fact that the power gains are relative to RPM range. Long tube headers give more consistent power, not necessarily more power. This means that the long tube headers will give power from mid-low RPMs through mid-high RPMs, whereas the power increase from shorty headers is limited to mid-range RPMs.
Considering that Karl wants the most HP from his exhaust, my recommendation would be a set of ceramic-coated SLP long-tube headers. The ceramic coating is an awesome insulator, it conducts almost no heat and yes, that is a good thing. Hot gas moves faster than cool gas, so keeping the exhaust gases hot moves them out of the engine bay faster, improving efficiency.
Mid-pipes are another subject I get a lot of questions on. What’s the difference between an X-pipe and an H-pipe anyway? First of all, a mid-pipe with a crossover is essential, it evens out exhaust pulses and the intermingling of the exhaust gasses equalizes backpressure between the two banks of the engine.
An X-pipe provides the path of least resistance, so to speak. Keeping the exhaust gases moving parallel to the walls of the tubing prevents “tumbling” and maximizes horsepower and efficiency by maintaining speed. While you won’t see as many horses with an h-pipe, they are touted for their low-end torque. H-pipes also encourage the “tumbling” effect of the exhaust gases, making them several decibels louder than an x-pipe. My recommendation for Karl here would be a shorty SLP catted x-pipe to match his headers.
This is the biggest factor in the actual sound. The headers and mid-pipe will affect the sound of your exhaust to a point, but nothing affects the sound of your ‘Stang more than the mufflers. Generally, the freer-flowing the exhaust, the more power you get. Even though Karl wants to boost horsepower, I would still recommend a system with chambered mufflers like a Magnaflow stainless cat-back system. This chambered-muffler system will give Karl the muscle car rumble he wants without that maddening drone at highway speeds.