I purchased and installed a 5" Diamond Eye Aluminized Exhaust w/ muffler delete + cat delete, here are my impressions.
HUGE. 5" is big, no joke. When I opened the box I was quite surprised at how much larger the 5" sections were compared to the 4" down pipe. There was also a box filled with clamps, instructions, and a warranty card.
I pulled all the pipes out for inspection and noticed a few flange lips had been bent during transit. I later tapped them back to shape with a ball peen hammer. Easy.
Instructions were extremely vague, with no information regarding the cat delete or muffler delete, or much else in fact. After counting all the pipes and doing a mock up on the kitchen floor (wife at work) it still didn't make sense. I was short clamps and had an extra large section of pipe. Oh well maybe it would make more sense when I started working on the truck.
I know I asked in another thread if it was possible to remove the stock exhaust for safe keeping. Well as soon as I started looking around I said F-it and busted out the Sawz-All then started chopping. Did keep the cat though, just in case for later.
: The 4" DP was a no go. Spent about 30 minutes trying different ways to get it up there. I partially cut off a firewall stud used to hold on the insulation which gained a bit more clearance bit still not enough. Next I unbolted the trans mount and jacked the trans up which tilted the engine forward hopefully giving more clearance. Still not enough but it was so close! With a little persuasion from my compothane hammer I did manage to tap it up all the way. Unfortunately in the process the turbo side sealing lip started to wrinkle up the foil on my firewall insulation. I remember reading about that before and expected it. I plan to smooth it back out later this week.
Laying across the motor I managed to get the DP stubby on the turbo and loosely clamped so I could rotate and position it before final tightening. The rest of the exhaust went in with a few positioning headaches, more than once I had to pull sections down and adjust. There was a LOT of tweaking to get everything just right. Clearance in some areas is JUST enough but most areas are excellent. The DP coming off the turbo surprisingly has nice clearance all the way down to the first joint. I did some engine loading and torque testing to check for contact points with the drive train flexing, but all was good. All bolted up the exhaust is very sturdy.
A couple things I didn't like is there isn't enough pipe in the individual sections to achieve a fully butted insertions. With everything butted tight (pipe A all the way into pipe B) there system was 4 inches too short and the hangers didn't line up. So I could only mate all joints 50% in order to get the correct overall length. IMHO this isn't right. The other after market systems I've installed, and the ones I've bent up myself, have always had 100% joint insertion. Now I don't think this is a problem because there's still quite a bit of sealing area there since the joint flares are huge, but it's not the proper way. Second, the clamps are very cheap. The clamp bases flare out and distort when tightening with just a wrench. Normally in the exhaust shops I've worked at, and everywhere else, we gun the clamps on. I tried to gun one on and the clamp went to jello. I'll have to replace it later. Third, I was shorted a 5" clamp so my installation isn't 100% complete yet but it's enough that it's drivable. I'm debating to tack weld the pipes anyway since these clamps are so weak. Also I still have a huge section of duplicate pipe that goes nowhere, I'm guessing it was just a mistake at the factory because the way it's flared will only allow it to fit on one place, and the clone to that pipe is already installed. Lastly I do have some contact with the tailpipe touching the mud flap. There was NO possible way to adjust this out without tensioning the hangers or sacrificing the sealing area on the flanges. I'll keep an eye on it and make changes later if need be. So some minor but annoying problems, but I'm aware this is a budget price point exhaust.
At idle it's terrible. Sounds exactly like the air mattress pump we use when camping. The '03-'04 guys have it made for idle sound quality. Overall volume when driving is livable, perhaps 10% louder than stock. Full throttle brings on a nice bark but isn't too obtrusive in my opinion. Windows open is a different story with the volume levels going up a lot more, but that's personal opinion as I know a lot of people want the aggressive tone. So overall sound volumes is much better than I expected. Overall sound quality is much worse than expected.
Overall not as much as I expected. Removing the cat and installing a 3" exhaust on my Supra was a night/day difference. In this case I feel maybe the turbo is spooling up a touch faster, but not much if anything for horsepower. The exhaust is the only mod so far other than coolant filtration. I suppose one of my main goals with the exhaust was to drop EGTs when towing and that goal has been met though I can't quantify it.
Awesome! Before exhaust 16.4mpg maximum, now I'm hitting over 20 all the time. What a huge difference! Very happy about this. That's with my mudders too.
Obviously very pleased with the mileage gains and dropping major EGTs for towing. Everything else is can be summed up in one word. Meh.
It's a $350 exhaust, what can I say.
Here's a video of it at idle.