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Highway Stars

Exhaust = Buick Grand National Reproduction Exhaust ( CAT BACK ) (option to add muffler with fixture checked option for $349))

Exhaust = Buick Grand National Reproduction Exhaust ( CAT BACK ) (option to add muffler with fixture checked option for $349))


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Product Description

GM Reproduction Stock Exhaust for a 1986 or 1987 Grand National or Turbo Regal.

GM Licensed Muffler is an associated/separate item . PLEASE BE SURE TO ADD ON THE MUFFLER OF YOUR CHOICE

(Please contact us for an exact shipping quote)

Finally, an affordable stock appearing, stock sounding GM service replacement exhaust system for your GN, TType or T with LC2 engine.  

Starting with 3” fully aluminized USA made pipe, the Y pipe is hand rolled and formed at the cat exit and beautifully welded to 2 x 2 ¼” pipes to form the Y. 

L and R over axle pipes continue to the crossflow muffler with internal architecture and stampings like the GM 25520009 you would buy at the Buick parts counter in the day. 

Tailpipes have the correct cuts, welded brackets and captive metric square nuts to make them indistinguishable from the OEM assembly line or OEM service replacement systems.

The muffler’s dual skin case has spot welds to baffles to the inner skin only, giving the exterior the correct GM smooth appearance.  We go a step further with powdercoated tail pipes in correct satin black for lasting beauty. 

All assemblies are actually fixture checked in our proprietary fixtures to assure consistency.  

Highway Stars also INCLUDES 4 cat studs and 4 nuts with washers, 6 correct style USA clamps and 2 hanger to tailpipe bolts. 

You must retain your original cat hanger, L and R rear hangers.  If you need the 2 tailpipe finger hangers, Highway Stars has reproduced EXACT reproductions.  

(Or you can purchase separately our BRAND NEW IDENTICAL TO FACTORY Tailpipe Hangers via Hanger, Exhaust Tailpipe - replaces GM# 25518527



 Once you buy the complete cat back system from us you are eligible to buy each of the 6 major components as an individual part should you ever need one, just like if you ordered them from GMSPO at the Buick dealer when they were available.  Multiple original assembly line and GM replacement systems were used to generate the data and fixtures for our replacement system.


These units can be purchase 1 of 2 ways. . . Your Choice :

A- You can purchase it without "FIXTURE CHECKED" stenciled on the muffler like a GMSPO service replacement.

B- You  can purchase it with the muffler stenciled: "FIXTURE CHECKED" like a factory original system 

We HIGHLY recommend this item is picked up in our warehouse.  If you must have it shipped, Please CALL FOR A SHIPPING QUOTE (shipping will need to be custom calculated to your location)

This unit is currently being sold as a COMPLETE SYSTEM. Individual components are not available at this time


A bit of history:  The original systems were one pre welded, pre aligned unit behind the Y pipe for assembly line expedition.  This muffler package was installed before the body drop and was never available as such at the GM parts counter. The part number stamped in the muffler was 25518343 and some later cars had  “FIXTURE CHECKED” stenciled on the muffler body.  Instead, a service replacement system was only available through GMSPO and consisted of a Y pipe, L and R over axle pipes, the muffler assembly with welded inlet pipes, and finally L and R tailpipes.  This allowed replacement at the dealer without dropping the rear axle assembly. This muffler is GM part 25520009 and correct for all 84-87 Turbo cars (except GNX for clearance reasons). Since the technician would be installing a 6 part cat back system after cutting off the OEM system, they were not stamped  “FIXTURE CHECKED” as they had the flexibility to be hand finished for alignment at point of installation.

Mathematically, the 2 2 ¼” pipes have an area larger than one 3” pipe,  7.95 in/ sq vs. 7.06 in/sq. The GM muffler has an open chamber center design and saves weight and ground clearance over 2 mufflers.  The only appearance difference on our system you may notice is smoother bends for better flow.  At this point in time, even low mile survivor cars have deteriorated original muffler internals due to acidic moisture attack, making them louder and prone to drone even though the dual wall muffler looks fine from the outside.  This system restores the original sound of the Turbo Regal as it left the Pontiac plant in 86-87. 


 Although this particular system is similar, it is not exact for the 1984 or 1985 vehicles. For the 84-85 cars, the round inlet Y pipe is being developed making a version of the system perfect for the 84-85 LM9 owners as the rest of the system is shared with all 4 years. 



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