installing dual glass packs

[85scotlongbed]

I recently received a 1985 Chevy Scottsdale with 90,000 one owner miles from an older relative.

Two mechanic friends of mine told me that replacing the original single exhaust and a standard muffler with dual glass pack mufflers would probably cause the truck to start using oil.

Has anyne else heard of this?

If yes, please advise.

Thanks