Alright so here is a dumb question I am sure, but searching is just getting me different opinions on similar subjects. I have a 2005 G35 6spd with Strup headers, Strup Test pipes, bassani catback, and MREV intake with 5/16" spacer.

Right now the strup test pipes make my exhaust rasp like a **** and I don't particularly like it. Is there a resonated test pipe out there that will give me next to nothing for rasp? If not, what is a good high flow cat to get. I was looking at the FI and Crawford cats but both a pretty expensive. If the Fast Intention cats are really $600 I think that is nuts considering I could buy a pair of high flow cats and cut/weld them into my strup test pipes for half that. Also are there any issues with cats failing early?

Thanks and like I said sorry for asking this similar question again, but the rasp is awful and I need a decent set of high flow cats or resonated test pipes to clean up the sound.

 

Sorry this doesn't answer your question but you got any videos of your bassani exhaust w/o the headers/test pipes? i just want to hear the sound

 

I think I have one, just give me a second to look.

 

Here you go, hope this helps.

Click here to watch G35-Bassani-Exhaust

 

thanks man, the shop im gonna go check out sells those along with other exhausts, wanted to see how it sounds.

 

It sounds really good and I am super happy with it. Throatier then the stock system, deep, and just sounds better. Might not be for everyone, but I am super happy with it. Glad the clip helped.

 

OK - so I'm not posting to sell you the FI HFC's - just to give you some info, etc.

Re: sudden rasp with header install

The catback system you have, and all of them for that fact, are not designed by any manufacturer to be used with headers, and most all of them, with the exception of Fast Intentions and now - possibly - Stillen. Stillen has recently introduced a set of HFC's and say there is no rasp - guaranteed - however if you see some reviews, I've heard more often there is rasp, than not - especially if not used with THEIR catback. Nothing is mentioned about headers.

The reason you have rasp, is because you have upset the flow dynamics, just above the systems tolerability, to handle the extra flow. Therefore, you have rasp, and less performance. Rasp is a result of the pulses not lining up properly, therefore performance loss will happen.

Now with the header install - you likely gained HP and TQ, though not as much as you could have, and possibly, you lost overall HP and TQ as well. Only a dyno will tell you that. Not all combinations work well together.

With all of that said - correcting the problem comes in many ways. First - a resonated testpipe will likely not help much at all - but that really depends on how much rasp you have, and when in the power band it starts, and if it goes away at higher RPMS. A good video may help to diagnose a better solution.

What you need to do, is restrict the flow 'a little bit' to adjust to the greater flow of the headers. This can be done with either HFC's or a different catback, or a combination. Also, the addition of a resonator may resolve it as well - as a little backpressure addition may just resolve it. Keep in mind - typically, these solutions will cost you a little HP and possibly raise low end TQ as well. The rough range is ~2-5 HP loss going from testpipes to HFC's.

Now - again, not to sell you: Fast Intentions has two flavors of CATS. Metallic and Ceramic. The Metallics are 300 cell and Ceramics are 400 Cell. The Metallic will perform better, as there is less restriction, and give you deeper sound, than the Ceramic. The Metallic will also last longer. Crawford does not offer a Metallic CAT though, so there is a consideration to be made on what CATS you purchase. Honestly - I don't know which other companies make Metallics as well - I'd tell you if I did - I really would.

So - another item - there is not guarantee that HFC's will solve the problem either. It's a crap shoot, honestly. I can better tell you, again, with some good video, a few runs, etc, to see how bad the rasp is. I can't take your word for it, as tolerance to rasp is subjective. Technically, any sound coming from a tailpipe is rasp.

I think the best solution for you would be Metallic HFC's and possible the addition of resonators - or maybe bigger resonators.

The Bassani system is virtually identical to the Stillen (in design, not part quality - not meaning Stillen is better/not better), with the exception of a far better X-pipe design and REALLY resonated tailpipes. So there isn't really much to change there other than larger resonators in the mid section.

The worst part is this. Adding larger resonators or HFC's could make the rasp worse! Removing the Bassani mid pipe resonators may resolve the problem, though making the system much louder...it may be the best balance overall.

Customizing an aftermarket exhaust, is never easy or cheap - in reality. If it were my car - I would test different resonators or remove them and see what you get to begin with. Rasp may disappear but you may get a bunch of drone in return...the downfall. It will be a trial and error scenario - the HFC's being the most expensive solution.

Hope that helps...

Rick

 

Thanks, I don't see how rasp would hinder performance though. In all honesty a stock manifold would cause worse pulse balances because the manifold has commingled runners. Anyways that is besides the point.

I could try ripping out the resonators and see what that does. Before I did the headers I left the stock manifolds on, installed the test pipes and the sucker rasped just as bad, so I am pretty confident the headers are not the issue, it is the pipes.

My brother has found me some magnaflow spun cats(metallic or ceramic) that he is finding out dimensions for and will get my strup test pipes cut and these cats welded in if they are short enough. So glad both my brothers own high hp mustangs and have messed with lots of crap. I wouldn't even have thought to look at magnaflow. Here are the cats if anyone is interested.

Metallic ones at the bottom 59970 http://www.car-sound.com/02product/u...al/599spun.asp

and the ceramic ones http://www.car-sound.com/02product/u...al/549spun.asp

So with that stuff mentioned I think if we buy those cats and weld them in that might be the best and most cost effective solution. What do you think?

 

OK - so rasp is the result of improperly balanced pulses...if they are not lined up properly and not balanced - the system is not as efficient as it could be...thereby affecting performance.

The CATS you linked to - are the same CATS that Fast Intentions uses - so I know they are good - and have gotten great reviews. they are made with different offsets - angled, straight and combinations.

EDIT: Oh yea - the stock manifolds are not that bad, compared to others - which is why the rest of the exhaust is made how it is - to adjust for certain shortcomings.

Rick

 

Thanks for the info on the cats, I will get some pictures when we get them done. I thought the cats looked familiar.

 

did you get the check engine light with the test pipes??? or did the ti tek screw in o2 sensor adapter help??? .....also on my car i get the rasp ...but it goes away after a few minutes of driving.....why is that??? as soon as it sits and cools down for like 10-15min it sounds like **** ...but after i drive it for 5min the rasp is like gone...odd if u ask me

 

where are you located? I have some FI resonated testpipes that i'm selling locally if you're interested.

 

I have read/heard this from a couple of people already. I dont know the answer but i am curious. Anyone know?