DID 1970 LT1 Have N11 mufflers, or just the standard muffler? would appreciate any info you guys may have. Thanks.

 

I think the LT-1s came with standard mufflers, but could be ordered with the optional N-11 off road exhaust

 

The only side exhaust system ever offered for a C3 was in 1969 and it was option N14. The N11 systems were for C2's.

 

who said anything about side exhaust N14, the question was the off road N11 option, available from 63-68

 

Sorry, I thought you asked about a 1970 LT-1. As I stated, the N-11 option was not available in 1970. If you meant to ask a different question, you might have gotten a different answer.

 

After checking several C3 option lists the only year I saw was 1968 for the N11 Off Road Exhaust, cost $36.90, numbered ordered 4,695 Maybe it was a dealer installed option in later years and not listed on the factory list?

 

Anything is "possible"...

 

All 70-72 LT-1's used the same muffler as the 70-72 454, GM part number 3943385 (LH), and 3943387 (RH). The only diference between the mufflers installed on base L-48's, and LT-1's, was the inlet pipe size, 2" for the L-48 verse 2 1/2" on the LT-1, the internal baffling was the same. The 68 "off road" mufflers were part numbers 3931803 (LH) and 3931804 (RH). The only factory usuage of the "803" or "804" mufflers ever, was on 68's ordered with RPO N11 Off Road Exhaust. N11 was discontinued at the end of 68, likely because the N14 Side Exhaust was introduced.

Noise regulations became an issue in 1969, and probably played into the off road option being discontinued. In 1970, Pontiac offered a vacuum operated exhuast cut out option on the GTO. Even though it was listed for "off road", it quickly ran afoul of the noise police, and was dropped after about 200 were built. The N14 side exhuast was going to be available on 70 Corvettes too, but was dropped before production began, likely because of noise regulations.

Back then there was nothing to stop a buyer from having a dealer install factory "off road" mufflers on an LT-1, but I doubt very many did. It was a lot cheaper to just buy a pair of glass pack mufflers. The first thing I remember most guys doing when they bought a new car, was runnig to the local speed shop, to buy a pair of Thrush or Cherry Bomb glass packs. That's not to say that we didn't buy parts from Chevrolet. Factory Chevrolet aluminum intakes and high lift cams, were very reasonably priced, and were just as good as or better than most after market ones, but when it came to mufflers, there were better options available from the aftermarket.