Most states say about the same regarding exhaust. That the system must exit away or out from under the passenger compartment.
In Texas as long as it is past the passenger compartment and exits to the rear or sides,you are good to go....it can before the rear axle on a pickup (without a camper) as long as it has turn downs.
Here is the written law:
20.15 Exhaust System - Every motor vehicle shall at all times be equipped with muffler in good working order and in constant operation.
Muffler defined: Muffler is a device consisting of a series of chambers or baffle plates or other mechanical design for the purpose of receiving exhaust gas from an internal combustion engine and/or turbine wheels for the purpose of receiving exhaust gas from a diesel engine, both of which are effective in reducing noise.
NOTE: On vehicles manufactured or equipped with a muffler and a turbo, the muffler must be present and in good working order.
The exhaust system includes the manifolds, gaskets, exhaust lines, mufflers, resonators, tailpiping, and supporting hardware.
Motor vehicles cannot be equipped with a muffler which is perforated or which was perforated and has been repaired, either by a muffler repair jacket or by patching or in any other way. In those cases where a muffler is perforated at the time of an inspection or has been perforated and has been repaired previous to the inspection, the muffler must be replaced or the vehicle rejected.
Some pickups are equipped with a camper or hard shell cover and are sometimes used for the transportation of passengers. The tailpipe should discharge the exhaust at the rear or sides. This truck modification will be considered as a passenger compartment.
The entire structure of a passenger vehicle or a motor home-type vehicle is considered a passenger compartment. The cab only of all other truck-type vehicles is considered passenger or luggage compartment.
If the vehicle is equipped with lake pipes or similar devices, such pipes or devices must be securely plated and bolted or capped.
Dual exhaust systems may be modified to single exhaust systems and single exhaust systems to dual exhaust systems, provided the modification does not violate requirements concerning exhaust emission systems.
The catalytic converter will be considered as a part of the exhaust system on all vehicles prior to 1984 year model and will be inspected only visually (if present) for leakage. On 1984 and later model light truck and passenger vehicles, the catalytic converter will be checked for presence and leakage. Flexible tubing which meets the requirements listed below may be used anywhere in the exhaust system.
NOTE: Inspection of exhaust systems covers the discharge of exhaust fumes and is not concerned with the noise level.
Inspection Procedure. The exhaust system shall be examined visually while the engine is running to determine efficiency of the system.
Inspect for and reject if:
Vehicle is not equipped with a muffler.
Any joint is loose or leaking, including manifolds. Does not include minor leakage at exhaust control valve (manifold damper or heat riser valve).
Manifold is cracked or broken causing leakage.
Holes, leaking seams, or patches on the muffler, resonators, exhaust pipe, tailpipe, or catalytic converter.
Exhaust system is not secured to the vehicle by mounting brackets designed for exhaust systems (wire is not acceptable).
Any brackets are loose, broken, or missing.
There is excessive vibration of exhaust line.
Any part of the exhaust system passes through the passenger compartment.
The tailpipe is broken, pinched, or eroded off to the extent to allow exhaust fumes to penetrate into the interior of the passenger compartment.
The tailpipe fails to discharge exhaust from the rear or sides or top of the passenger compartment of the vehicle.
NOTE: Holes in the exhaust system made by the manufacturer for drainage are not cause for rejection. The tailpipe must direct the exhaust fumes out from under the passenger compartment.
NOTE: On pickups not equipped with a camper or hard shell cover, holes or leaks in the tailpipe extending beyond the passenger compartment will not be cause for rejection.
