Hi everyone:

I want to purchase a set of high flow cats. If you have the injen straight tip, could you describe the sound/power increases in conjunction with the cats? Which hfc will give no rasp or ugly ricer sound?

I'm leaning towards the Helix HFC and possible the Ultimate racing HFC.

Thanks!

ravi

 

ravi,

I have a G35 Coupe with the Injen SES Straight Tip with Kinetix HF Cats. The system was really loud - deep & throaty, but no rasp. The power was very noticeable, but too loud in the cabin.

I just installed the Alphawerks Headers with two Mganaflow 4" Round - 24" resonator pipes. The sound is very nice. The power and acceleration has increased considerably. The exhaust system now has a real deep tone yet very mellow in the cabin. I'm happy with my setup of Injen mufflers, Kinetix Cats, Magnaflow 24" resonators and Alphawerks Headers exhaust system.

 

Hrmm...

Thanks for the advice. Kinetix seems like a good buy, but I'm not trying to become deaf so the resonators seem like a good idea. What do they cost and do they make you lose hp? Can they be purchased at any exhaust shop?

Its eery b/c I want the Alphawerk headers also. So my full combo will be AW Headers, Injen Straight tip, some hfc, and maybe some resonator to keep the sounds down. What component do you feel netted you the best gains?

Thanks for your insight.

ravi

 

I love the Alphawerks Headers. The car after a ECU reset is responding very well. The rpm's are climbing much faster and the top end is much improved. The Alphas are well constructed, great quality and a reasonable price. The HF Cats also opened up the exhaust system. Avalon Racing (see vendor classifeds) is selling the headers for only $619 +$20 shipping. The header install was only $275. IMO - A Great Mod Buy!

The Magnaflow XL Powerpacks are 4" round with 24" in length. I'm not sure you can fit those on your 350Z (maybe 18" or 20"). It is a straight through free flow SS muffler/resonator pipe. Any Mangaflow dealer can get them. I think they run about $45 to $50 a piece. The performance should not be effected, and it has quieted down the Injen/HF Cats while reducing the exhaust's vibrations. I'm really pleased with the sound and the performance.

I hope that helps - good luck.
Keith

 

where did you get the install?

 

I got the header & resonator pipes installed at Chino Valley Muffler in Chino, ask for Tom (909.627.2708). The shop is located off the 60 FWY at Central Ave. He has done some good exhaust work on my G35 previously. This was his first header install on a G or Z. It took about 5 1/2 hours, but he said he will be able to do it faster next time. He will install them for the $275 price.

 

im looking to do the same setup in my 350z. all i have now is the jwt popcharger, but i am adding a plenum (probably motordyne), and then am looking to add the injen straight tip and the helix or kinetix HFC. ravi, keep me updated with what you think is the best combo for HFC and the injen SES

 

Sure thing--I really want to get the helix b/c the price is good and they are metal substrate (all this means is they wont blow up on you lol). I want agressive/exotic sound and not ricey, so I'm probably going to need the resonators to tone it down a bit. As long as hp isnt affected I dont mind.

keith N, thanks for your input--it means a lot. I don't want to make a bad choice b/c the Injen is pretty loud with stock cats and with complete exhaust (headers + hfc) it'll be nuts I'm sure. The resonators is a good idea. Where do they weld these at?
I'll update this thread based on my decision.

ravi

 

Guys,
Here's a link with info. and pics from G35Driver.com from Gsedan35 (he's also on this forum) regarding his custom sedan Injen setup. He used the Injen Tips, Magnaflow resonators, Magnaflow HF Cats & Magnaflow X Pipe. It is a really sweet custom exhaust. He has some great info. on suspension and exhaust.

http://g35driver.com/forums/showthread.php?t=50369

Ravi - The Magnaflow resonators were welded to replace the Injen resonator pipes (12 "to 14" long). This really calmed down the tone and vibration in the system. I love the looks of the Injen, but I have some fiberglass blowing out of the system. Injen has not been supportive about resolving the situation. For me, the sound level with the HF Cats was too loud during freeway driving. It is probably 25% to 35% better regarding the noise level - deep, mean & different.

 

Great.

 

I just added a set of Crawford HF Catsover the weekend to my injen Straight tip exhaust. Before I added the HF cats the only thing done to my car was the exhaust and Crawford Plenum. Over the weekend I added a JWT PopCharger and the HF Cats. Let me tell you the Z has come alive. The sounds is sick, it is really not alot louder than it was before but during a downshift or just slowing down the car sounds mean as hell. I thought about going FI but I think that I have changed my mind and know I am going to do heads and cams and then probally build the tranny up. But I promise you will love the sound of HF Cats with the injen.

 

great to hear... try posting a sound clip or video when you get a chance. do you feel any difference in power when you drive your car, compared to when it was stock. i am considering similar mods, and i will not be going to FI anytime soon. the main thing for me is, if i am not going to notice any power gains, i may just wait until i have the funds for FI in the future. I am considering a similar setup, my plan is:

1. jwt popcharger (100)
2. kinetix intake manifold (700)
3. kintetix HF cats (300)
4. injen super SES straight tip exhaust (500 used, hopefully)

if i cant get any real performance gains with these mods, i may just get the jwt popcharger and call it quits for a few years, until i have money to waste.

 

From the car being bone stock to the way it is know, The seat of the pants dyno feels like about 60 hp. Now I know that there is no way in hell I added 60 hp with the few mods that I have done but it sure does feel a hell of alot better.

 

awesome... stage one of mods is about to begin

 

Great news...do you guys think you can get caught with high flow cats just driving around? I'm curious what you guys think b/c I'm in California and don't want to be hassled/get fined.

Thanks for your suggestions guys.

ravi

 

If you are concerned with noise, and are running a very free-flowing exhaust system setup, resonators or high flow catalyzers are recommended. By running straight pipes, (no catalytic converters) the car will be extremely loud, and will more than likely exceed 100db, which is audibly double the maximum allowed limit of 95db.

Every three decibels is roughly the equivalent of two times the audible sound output.

Some form of resonators are recommended, especially on straight through systems, as the resonators function to reflect some of the sound waves emitted from the exhaust. When the two sound waves collide, the sound is cancelled, resulting in a much more pleasant, cleaner exhaust note. Depending on the design of the resonator, the affect on the exhaust flow and exhaust gas velocity should be very minimal.

95db is the maximum allowed limit in California, and catalytic converters are also required. California Highway Patrol has become more knowledgeable on the modification of cars through the efforts of SEMA and SEMA members. Many officers are now knowledgeable on what to look for nowadays, so mod responsibly!

 

Tanabe -
Thanks, good info. on exhaust sound and heads up on CHP.

 

But HFC are ok right? I dont want test pipes b/c even with resonators there is some rasp. I heard with headers sometimes even the hfc rasp.

Any suggestions on HFC in california? Basically will it be at or around the 95 db level? So many people have been using them in cali, so I assume they are not super loud.

ravi

 

Hello Ravi

Any quality constructed HFC should suffice. Causes for raspiness in the exhaust note can vary. Quality and type of construction of materials used in the exhaust system are often a culprit, as lower quality construction, and/or simply bad gaskets can cause various rattles and vibrations which are then amplified through the exhaust.

The job of the muffler is to dampen the sound of combustion occuring in the engine, and on a performance application, it must perform this function without drastically affecting flow. When the exhaust system is completely free flowing, the muffler in a sense has much more work to do, and most are not accoustically designed to cancel out that level of noise. There are some exceptions to this rule, which generally involve the internal construction of the muffler, and/or vehicle type. Some types of cars, such as rotaries, are generally louder vehicles, where sound cannot be seriously dampened without an affect on exhaust flow.

Particularly on turbocharged cars, the high heat of the exhaust gasses can quickly deteriorate the internal packing material (fiberglass is most common) found within the muffler, virtually hollowing out the muffler canister in a surprisingly short amount of time. This is also a common cause of 'raspiness' as the muffler loses it's ability to dampen the sound with age and useage.

In general, the higher the performance and efficiency of an exhaust system, the louder the car can potetially be. There are of course some exceptions, and it is always wise to do research on the internal construction and specifications of the muffler and exhaust manufacturers you are interested in when building a full exhaust system so that you can acheive the power, sound levels and durability you have in mind.

 

i'm n/a and i think my injen straight tip is throwing fiberglass shards onto my rear bumper...i've heard of this problem with G35s but not with the Z

do all aftermarket exhausts do this?? i know it's not dust!!