ive heard that drilling a half inch hole next to my outlet port on my stock muffler can add a few horses and improve sound what do u think????????? ------------------ CHRIS 1983 firebird transam

Yea it does increase sound and flow a bit but the majority of exhuast will still flow through the muffler. I did it to mine a day before I got a new set on it. 1in circle saw 5 holes it sounded mean. On the other side of the coin "this is ify teritory" Its possible by drilling a hole could create a vaccume effect and suck up moisture and debre but its highly unlikely! Drill away!
SSC

wut about drilling in the IN side?

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88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

Now where'd I put my drill? Try to make the holes not so obvious. Just another reason for a cop to pull you over for an emissions check-up.

Matt

top

This is a really stupid thing to do. You'll make it louder, but you won't gain any power. Upstream restrictions will dictate power, not the muffler outlet.

And, you're putting exhaust under the passanger compartment. Not a smart idea. Which is also why it is illegal, not because of noise.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet (Holley 3310 on the way), GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

I agree, it's not a smart idea. Sounds like something a rice "rocket" would do. Just buy aftermarket exhast.