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**MikeB** · 10-21-2018, 01:29 PM

The larger the bend radius the better. But if you don't have a lot of room for a large, gradual bend at least use a mandrel bent section for the down pipe instead of a muffler shop "crush bend". I would bet that a 2-1/4" system with mandrel bends throughout will outflow a 2-1/2" system with crush bends.

On another note, I think it was David Vizard who did some flow measurement tests using mufflers that were one size larger than the exhaust pipes. Even if the mufflers are the straight-through type, going to a larger size noticeably increased flow. (Of course you'll need adapters.) And don't even use a stock-type muffler that necks down internally. The 2-1/4" Heartthrob mufflers I mentioned above necked down to approximately 1-7/8" internally

and I have seen that with other cheap OE-replacement mufflers. I would have been better off with a single 2-1/2" system!

10-21-2018, 01:29 PM	#17
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,440	Re: 2.5" vs. 2" exhaust The larger the bend radius the better. But if you don't have a lot of room for a large, gradual bend at least use a mandrel bent section for the down pipe instead of a muffler shop "crush bend". I would bet that a 2-1/4" system with mandrel bends throughout will outflow a 2-1/2" system with crush bends. On another note, I think it was David Vizard who did some flow measurement tests using mufflers that were one size larger than the exhaust pipes. Even if the mufflers are the straight-through type, going to a larger size noticeably increased flow. (Of course you'll need adapters.) And don't even use a stock-type muffler that necks down internally. The 2-1/4" Heartthrob mufflers I mentioned above necked down to approximately 1-7/8" internally and I have seen that with other cheap OE-replacement mufflers. I would have been better off with a single 2-1/2" system! __________________ Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 23 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!