So I just got an 05 Coupe 6MT with the rev up engine. It's had some work done to it already but there's just a couple things I want to add before I do a final tune on it. It has a CAI (no idea what kind), DC shorty headers, cats deleted, factory muffler, 6-puck clutch and lightweight one-piece flywheel, and a re-built transmission with 5k on it.

So first is the exhaust. I don't like the way it sounds much. It's really raspy around 3000rpm. I only like the raspy sound on V8's. I want it to sound deep and rumbly on this car. I looked around a thread on here, coupe exhaust compilation and really only found a couple I like the sound of. I really like the Motordyne shockwave and the Agency Power Ti but the prices are much more than I want to pay and all seem to be catback systems. Do I really need a catback or can I find just the mufflers? I have an exhaust shop that's pretty cheap on their custom work and they do a real good job. Are there any just standalone mufflers out there with a deep rumble that don't cost an arm and a leg??

And on to the spacer. I looked and there's no spacer on this thing. It's the revup engine so is there a specific spacer for these or are they the same as the DE? I also noticed there's a 5/16" and a 1/2", would the 1/2" be better? Also I saw some are black and some look metal, are the black ones plastic? They're a lot cheaper, are they as reliable?

Also, I've read some saying I'd need the MREV2 lower plenum on the revup? That thing isn't too cheap, and with the cost of the spacer included, wouldn't it make more sense to spend an extra $100 and just get a better manifold altogether? The Kinetix Velocity intake manifold is $789 and claims 30hp gain, and looks way better than stock. It would end up being about the same price for the MREV2 and a spacer and possibly less gain, and stock looks. Opinions?

 

For starters lets have a little discussion about useable powerband compared to PEAK horsepower gains.

What rpm range does your engine normally see? Is this a track car that only uses 4k-7k rpm, if so then yes the Kinetix manifold is a great choice because it has great peak power, midrange however there are better options. If this is a daily driver that usually spends it's time around 2k-4k then the MREV2 and 5/16th spacer is what you want, there are substantial gains of +20whp across the midrange that other intakes like Kinetix do not provide.

Stay away from the polymer spacers, their gains are identical to the aluminum ones but longevity is questionable, some brands are particularly notorious for cracking (blox) but there is an inherent weakness that stems from how thin the material is around the bolt holes and eventually they will ALL crack. Aluminum costs a bit more but will last for the life of the vehicle. Motordyne is by far the most reputable brand to use for these components, you get what you pay for.

As for the exhaust... this is something I struggle with as well, imo this engine just cannot make GREAT sounding noise if it's too loud and unfortunately any of the dual exhaust systems you will find are all loud. Some are deafeningly loud while others are a "quieter option" but still incredibly loud. For pure sound your best option is the stock coupe midpipe and muffler, resonated HFC will make it a little deeper and more burble without adding too much noise, test pipes (even the very nice ART pipes) will introduce a lot of unwanted noise/rasp/drone on the stock system.

However, the dual exhaust systems do provide better power gains... I recently got rid of my Fast Intentions traditional exhaust because even though it is definitely one of the quieter options it was still just too loud for my tastes, I'm currently back with my stock cat back system but I have the FI RHFC on still because the OEM cats are VERY restrictive and you can feel a difference.

If I add any other power adders to this car I'll probably go straight for a Vortech supercharger, with this exhaust setup and the MREV2/spacer it would be about 350whp or so.

 

It's a daily driver but to be honest I wouldn't mind the top end power. I for sure don't drive it like a grandma. I found someone with similar mods plus cams that made pretty massive midrange gains with the Kinetix manifold over the spacer and MREV. So that's got me curious.

As far as exhaust I for sure don't want it crazy loud. I heard the Nismo exhaust and I really like that one too although I know it's probably pricy. Are there standalone mufflers for this thing? Axle back?

 

Your major issue with crap exhaust sound is headers into a catless set-up. As cleric mentioned high flow cats will mellow out the ugly sound and rasp a bit but the headers are throwing a lot of air into the exhaust with mis-matched pipe sizes so you'll never get good sound with that arrangement. Good exhausts aren't cheap for a reason, good R&D and quality components make them worth every dollar and they're a bargain if you can find them used. Often they'll be half of the original price and unless they've lived in a cold environment where the roads are salted or de-iced with chemicals they usually don't wear out.

Be careful how far you go with mods to increase HP. Unless you are willing to go forced induction you'll spend way more money than you want to for gains of 30-40 HP.

 

Cams are fine for a race motor, for a DD they shift power out of the low end which isn't all that great.

 

Couldn't I just add another resonator in there to quiet the rasp? And what mismatched pipe sizes? I looked under there today and it's all the same from the headers back, as far as I can tell. I just feel like catbacks are way too expensive. I got a Flowmaster DBX, custom Y-pipe and custom bent piping all the way back, custom hangers, and a nice tip on my Sequoia for $600. I feel like spending double that on just the parts, plus labor is just asinine. There has to be something I'll be satisfied with both sound wise and cost wise. Sorry, I'm Mr. frugal to a T.

I don't plan on going crazy with mods at all. I just want to get the exhaust and intake manifold figured out before I get it dyno tuned. After the tune, I'm done. The only other thing I'm possibly considering is maybe some wider tires on the back but honestly I haven't really gotten them to break loose yet, and I haven't been easy on it, so I'll probably leave them alone.

 

Good response and answers!
Exhaust systems, regardless of which system you buy there will always be an RPM range where the rasp momentarily shows up! What you currently have is a mismatched system beginning with test pipes! Since you're not willing to spend those big $$ for a new proven manufactured system watch our Marketplace under private classified for a member selling their Motordyne or HKS system. They generally sell for half of retail or less. Stay away from Vortech unless you have tight internals!
Gary