cLAYH

After getting quotes of $600-$900CDN for a 4" exhaust system for my truck I decided to try building one myself.

Seems most shops are leery of trying to build a system that goes around the t-case. So I bought 15ft of 4" flex exhaust and went straight from the factory 3" downpipe straight back over the axle and out the back.

It went farily easy, hardest part was over the axle. There isn't much ridgidty to the flex pipe so while it easily navigatied around the t-case it was difficult to get it to maintain shape going over the axle. This resulted in needing to use more hangers.

I did not use a muffler and went stright out the back as opposed to going 90* out the passenger side. I avoided doing this because for one, any sharp bends are bad and two, when I pick my wife up sometimes the exhaust would blow into the cab when she opened the door. I also used a turndown pipe at the end. Someone else here said it cut the noise and I have to agree. Having it pointed at the ground definetly seems to deaden it a bit. Thanks for the tip.


Impressions:

Noise: Not much louder than the stock 3" system with muffler. The wife says she barely notices a difference. Only really noticable on hard acceleraton. I may end up putting a free flow muffler on we'll see.

Boost: Not sure about acceleration seems like it might be a bit better. Boost is up 2.5psi from 25.5psi to 28psi. So power must be better I guess.

EGTS: still get pretty high on prolonged WOT acceleration. Just as high as before BUT slower to get there and MUCH faster coming down.

MPG: too soon to tell, but I'm guessing 1MPG?

We will see how this works out. Not sure how durable this stuff is especially the loop over the axle. It cost about $150CDN and a few hours of my time. Having a chop saw, mig welder and torch helped a fair bit. I figure if it doesn't hold up I'll buy a 4" t-case back system and use the 4" flex pipe to go around the t-case. I've been told that after awhile it stiffens up se we will see.

y-knot

Sounds like a waste of your $150.00. There are many places that sell 4" exhaust systems for 299.99 several even lower. I think a better solution would have been to save up till you had the money and buy yourself a real exhaust system.

cLAYH

Unfortunatly here in Canada we have to pay shipping and duty on anything imported which often drives up the cost of goods. As well we lose about 30% on the exchange rate. So when you pay $300 for a system I pay $600.

Also this isn't the typical flex exhaust you find a your local auto parts store. I am a Journyman Heavy Duty Mechanic and this flex pipe is used on most big rigs in the 6" size going from the turbo to the stacks. Next time your are filling up at a truck stop have a look under the cab of a big rig, you'll see what I mean. I'm 220lbs and can stand on this stuff without it crushing. Also all connections were made using the proper Torc-Tite Lap clamps, not the u-bolt style crush clamps.

So far its been on 3 days and hasn't shifted so I'm pretty pleased with it and I seem to have the same results as those with the pre-fabbed systems. I may have spent more time on it and gotten a little dirtier but I think it was money well spent.

Grey Wolf

A redneck from Canada, eh As long as it works for you, that's what matters!

Monty

Be sure and watch the flex for rusting problems very carefully. Since 150 was the price of the system. I take it you used galvanized flex? Galvanized flex is WELL known to rust out in no time down here. Where your at would be even worse with road salt etc. Just be sure and watch it.

Graeme

Sounds good. Hopefully it lasts well for you. Do you have any pictures?

cLAYH

Yep it is the galvanized. I cheaped out in case it doesn't work. If it holds up well and works ok I'll step up to the SS pipe later. If it doesn't work I figure I'll still use the flex pipe around the t-case and use the stock exhaust as a template and have a 4" hoop made up. Time will tell I guess.

I have been told by some of the older mechanics in our shop that the flex pipe usually stiffens up quite a bit after its been heated a few times and will rust in to its shape. I noticed that the trucks at work had galvanized flex pipe on them and are holding up fine after 15 years but the pipe is under the cab and not subjected very much to road salt.

Sorry no pics, will see if I can get some this week.

TexasBlake

I've got 4" flex pipe exhaust. Works just fine for me.

PumpDaddy

My 4" complete exhaust for mine only cost $328.00 and 2 hours to install. Looks great and sounds greater. The wife said it looks like a big stove pipe sticking out the side I just hope she doesn't try to dump some coal under the hood to get more smoke

RedWhiteDiesel

Y-knot - who sells these 4" systems for so cheap? And are they stainless steel? I really need to step it up, and if i can get it for that price, i want it!

dana70

Good idea, The flex hose hadn't really ocurred to me, but what I did was to get a piece of 4" aluminized pipeand several long and short 45s and a good grade low restiction muffler and cobble one up quick and shoot it out in front of the rear wheel well. I sawed off a piece of the 4" pipe and made a tail piece and even if I do say so myself it sounds like one of the big boys. Big sound, more boost and less milage (only because I like to hear it). The flex would sound like the ticket to get me over the rear axel though. Total cost of my job. $189. P.S. thanks again for the suggestion Monty

cLAYH

I'm in Alberta where the main industry is oil/gas and ranching. We have LOTS of Rednecks.

So far so good. Still nice and tight.

EXCESSIVE FORCE

cLAYH,Don't let 'em get ya down.I did the same thing only i stopped about 2 feet behind the cab,and installed a turndown.Sounds great,especially when you let off to shift.

Oh,and by the way it's been like that for well over a year without ANY problems.

Redleg

I cut mine short too, just keep in mind, when you go to work under there after trimming, everything you touch is gonna be covered in soot and be a bit more of a pain to work on.

dana70

Mine actually clears the outide of the bed/fender. Well.....it kind of looks like a big sewer pipe sticking out in front of the wheel well opening. It goes out far enough that I haven't noticed any soot yet, maybe I need to crank down on my fuel screw some more.