FI LTHs significantly better than HFCs?
 

So I am looking for opinions from people with the Fast intentions LTHs. I currently have Fast intentions resonated HFCs and exhaust with 18" resonators. I am thinking of getting LTHs with built in race HFCs. My question to all of you with LTHs is if there was a big noticeable difference with them. Will the gains be enough for me to feel with the butt dyno or just show up on the actual dyno? They're pricey so I am wondering if the gains from HFCs will be worth it or if I will be left sort of regretting the cost for gains that I won't really feel much? Your thoughts and dynos if you have them/want to share would be appreciated.

sub'd for feedback

My guess would be that it depends on whether you're installing them yourself or paying someone to do it. Header installs take a while.

Would have it done at Fats Intentions where they weld 100 cell HFCs in behind the LTHs and in front of the exhaust so I won';t have the usual LTH/TP fuel smell. just trying to figure out if it's worth it or if I should stop throwing money at NA mods and stick with what I have.

If you're paying $1500+ for the headers and then a couple hundred bucks in labor and only make another 5-10whp, will you be pissed off? I would be.

So just 5-10 who and trq throughout the rev range? I was hoping it would be more like 10 who throughout the rev range + 8-15 trq throughout. I was hoping those with them could chime in on wether or not it made a difference they could actually feel and not just on dyno sheets.

FI LTHs significantly better than HFCs?
 

Compared to stock, sure you'd feel a difference. Going from HFCs, I'm not so sure. You'd probably get far more out of a set of gears. The Motordyne manifold also has some nice torque gains. Both of those together would still be cheaper than the headers.

I doubt you would feel anything less than a 10whp increase unless your butt dyno is incredibly sensitive.

I have both of those. Gears made a big diff, the m370 not so much.

Then headers are really all you've got left to do. I'm not convinced you would see a huge difference from HFCs.

I'm debating headers or some wheels. Performance, possibly only marginal, vs looks. Or I could build myself a new computer, haha.

Buy the wheels. You're at the point of diminishing returns on NA mods.

I would dump the m370 if I do headers. If I could end up north of 320 whp with around 8 - 15 trq throughout the revrange,, I'd probably not be too disappointed.

I have garage line LTH (eBay obx $300 header). Design is almost the same as the FI except mine doesn't have the star thing that's supposed to help with savaging in the collector. The before and after dyno here is I installed the LTH, added some Helmholtz resonators right where the LTH meets the X pipe in my CBE, and I removed the top speed muffler and just made straight pipes using the TS tips. The before had OEM header and OEM cats. Its a good increase for a very cheap $300 spent!! Both are untuned and running a little rich which is safe. But since you have hfc now and you want FI LTH and paying someone to do it...I say no way in hell! Way to much money for no where near the increase I got.

16.30-19.09 Tq thought the power band and 10.93-16.93 Hp. Although my best run that we didn't use to compare the before and after was even higher at 295.33 hp and 244.32 tq.

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Why would you get rid of the manifold if you did the headers?

It also may be more effective to start cutting weight. A set of two piece rotors cost less than headers, and you'll definitely notice dropping that much unsprung weight.

Unsprung and rotational, double whammy.

The manifild didn't do much for me and was pretty disappointing so if I did the headers, I would remove them for more peak and to sell to save some money.

Did you do a base line dyno yet. If you are around 300hp now with the hfc's. The money you spend for the lth's and install would hard to hard to justify I think.

My base line was 282hp and 230 torque for my Nismo. After the lth's, 12" resonators, cbe, the Stillen 3g's and some other stuff. My numbers are 334hp and 279 torque.

Rusty, if the LTHs got me close to your numbers, I would be happy, but it is looking doubtful. I am at 307whp, 252 trq. If I drop the m370 since it's not helping me as much as I was hoping in the midrange, I would probably be around 310 or a bit over. A realistic but possibly lsihgtly optimistci number after the LTHs would probably be around 320whp, not sure about trq. I'm not sure if that's enough for the cost. If I could get 325 whp, 265 trq with aroudn adouble digit increase throughout the rev range, I would be more inclined to go for it. I am not sure if that is a reasonable expectation or not though.

You're at 307hp now. To pick up 13, hopefully alittle more hp for $1,500 plus install. (about 6+hrs for labor) You have to think hard about choking down that pill. You already spent the money on the hfc's. Getting the lth's now meaning that the money you spent on the hfc's is wasted. Unless you can get your money back on of them. Most people I seen with the lth's are about 320~hp and about 265~torque. That's about the avg.

Think now because I'm older (57). I'm a little wiser with my money. I think my mods through a whole lot better now. LOL Instead of "hey, lets throw this on and see what it will do". To "ok, if I do this, what is the cost to me and can I expect from it, and what else does it effect".

I am thinking of seeing if Tony can weld in the race cats like he was going to do for the LTHs, but install ART pipes instead. I figure if the race cats weren't going to really restrict gains form the LTHs, they shouldn't affect ART pipes much either. ART pipes might not get me as much as LThs, but it shouldn't be too far off and it will save me quite a bit of money and make it much eaiser if I ever need to go stock in the future for smog. I will call Tony and see if that's possible.

Out of curiosity from this - does anyone have experience with how bad the smell is with TPs over HFCs?


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It's because you're smelling pure exhaust fumes made up of carbon monoxide, nitrogen oxides, raw hydrocarbons, and ozone. A cat smells like water, carbon dioxide, nitrogen, and oxygen. Don't ask me why but I love raw exhaust! I hate the smell of catted exhaust fumes. Its night and day though on smelling something vs not really anything.