Who sells a decent exhaust?

[blazer74]

IMHO something's are better left to those who do this everyday, plus if you have any problems there should be a warranty.

I've been both routes, cheap kits don't last and if you don't know what brand headers they are to matchup a system.

If it's just a beater and your going to tear it up simpler is better.

Either way a I had a shop install. Exhaust work is not for me, that's just me tho.

 

[82355]

I don't have an exhaust shop in my town.

Martin

 

[blazer74]

There goes that option.

 

[vandelay industries]

1) So what would you recommend for a stock 4.3 that will rarely see north of 3000 rpm?

2) Same question, but with a crate 350.

2a) Same question but the crate 350 may see 4500rpm+ every now and then


3) What the factory (gm at least) seems to like doing these days is to "Y" after the converter and have two mufflers (appears to be dual exhaust but isn't). Is this done for less restriction or less noise or both?

 

[dyeager535]

Little chart here makes it fairly easy: http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/
Obviously that is a simplification, impossible to get it exact since engine output is not a constant. Among other variables like exhaust cooling, converter re-heating, etc.

You don't need the same flow at low RPM as you do high RPM (look at most dyno graphs) and with trucks many are looking for good low end power. Smaller exhaust will be more applicable in that case, but obviously you will trade off as RPM's climb if the motors power is increasing.

You can size for maximum HP, but if you don't spend most of your time there, is it worth the loss in low end?

Speaking from strictly a butt dyno perspective (and datalog numbers showing AFR didn't change measurably), from dual 2.5's with long tube headers/no muffler to single 3" with shorter headers and fairly aggressive open single muffler changed the performance on the same engine in no way I could tell.

The newer factory after cat Y might be packaging and noise reduction combined. Easier to fit two smaller mufflers, that are more efficient at reducing noise, and together still flow equal to a single less restrictive (and louder) muffler. The OEM's generally seem to spend a lot more effort on exhaust now than they used to. I think the old adage holds true though...if they could get away without it, they would.

 

[Blue85]

I agree with having a shop bend it up on the spot. Usually cheaper than a mail order kit, gets done faster, everything gets welded and any leaks are THEIR problem. You also have full options of routing, diameter, etc. based on how your truck is set up and the muffler/cat you want to use. So order your headers/mufflers/cat/tips yourself and carry them to the shop. The only difficulty is that in some areas shops won't/can't work on anything non-stock. If you ask around, you can probably find somebody kind of flexible though.

My rule of thumb for clamped joints is that the number of them under the truck should never exceed the number of leaks you want. You can try fully welding it yourself, but it's not as easy as it sounds to get a 360 degree weld with the pipes on the vehicle. The shop guys get a lot of practice at it, though. I like having a joint somewhere so the system can be removed without cutting and that will also allow you to finish weld on the floor (sometimes this can be at the header collector).