NA Ka24de Catback sizing/upgrades.

[Mr240dude]

Can't seem to find concrete answers on this argued topic, however I plan to buy a catback system for my Na ka24de. Is there a difference between 2.5 or 3inch? I notice alot of these systems come in 3 inches particularly for the NA, howeever is this too much? I ask because my test pipe is 3 inches, so would that mean I would need a 3 inch catback or is it possible to bolt the 2.5 on. I probably won't turbo for a while, that's not realistic anytime soon, but is a thought. Since we're on the subject, I notice downpipes for ka24's are 2.5 inlet, am I going to have an issue bolting that to the test pipe as well? Worth it as far as performance? I want to try an achieve at least 170 horses when it's all done and said with.

[Hooked on 240]

Ive had 2.5 and 3in on non turbos KAs. 3 is too loud.
If you get an exhaust and on a budget get a megan racing header or ebay one. same thing. Have someone look over the welds before installing (Reason is they mass produce and sell cheap) get either a test pipe (fake cat) or a high flow cat. Next you want a resonator and muffler. Id suggest a BRM catback. They sound AMAZING. If you get a dual tip over the watermelon cannon this is what it is from maganflow (http://www.ebay.com/itm/MagnaFlow-14815 ... 1585wt_804) I just bought another for my V8 project. I swear by them and looks stock enough you wont get harassed.


If your doing a NA build,
My setup for my daily:
Header
Cat delete (or high flow is a option)
catback. If you get a coffee can at the end your only asking for trouble.
~s13 KA24de
~2 S13 Exhaust cams. Turn the exhaust cam thats going in the intake side back (counterclock wise) 4 teeth.
~S14 intake manifold (has no secondary butterfly valve. (Or do ITBS )

~Also Xcessive has a intake manifold forsale but id buy it if you start to get into pistons/turbo, etc.
~Taking the emmions stuff off only makes your engine bay look better and wont help HP wise. I did it bc well it looks like a freaking mess from the factory.



These cars are rated 155hp from nissan. In reality its around 124hpish to the crank.
Doing all the above will probably give you 10hp max.

If you want anymore info Ill answer anything, KA's are my specialty and know they better then my gf Facebook @ Jeff Morgan. Pic of my old S13 is me.

[Mr240dude]

Wow so adding a header,test pipe and catback will only yield around 10hp?? As far as size you said 3inches is loud but it wouldn't decrease performance? I have second thoughts now getting one. Right now my car is loud, intake,3inch test pipe and can muffler welded to stock exhaust. I guess there's no way 165-170 horses can be achieved with all those bolt ons huh.

[Hooked on 240]

If you're going by rated Hp in imaginary land then ya 170hp is no problem haha
And as for the performance.. 3inches is too much on a stock NA KA24DE or any 4cyl. 2.5 is good enough. Plus the header is 2.5, so just get a matching testpipe and catback.

So wait. What is your exhaust now?

Stock header -> 3in test pipe -> stock piping -> Can muffler?

If so that sounds like a disaster lol, Spend 200 and get a full header back exhaust on ebay or save up and do it right

[Hooked on 240]

Also, if you scroll up to the BRM exhaust thread sticky this is stated to further prove the 3inch theory:

"Keep in mind that 2.5" is a significant increase in size over the stock system, and there are far less bends / restrictions in our system. Unless you're pushing 400+ hp, there's really no need for 3"

[Mr240dude]

If you're going by rated Hp in imaginary land then ya 170hp is no problem haha
And as for the performance.. 3inches is too much on a stock NA KA24DE or any 4cyl. 2.5 is good enough. Plus the header is 2.5, so just get a matching testpipe and catback.

So wait. What is your exhaust now?

Stock header -> 3in test pipe -> stock piping -> Can muffler?

If so that sounds like a disaster lol, Spend 200 and get a full header back exhaust on ebay or save up and do it right

Yeah haha and it dont sound all that bad either. Well that sucks now I need to buy another test pipe since 3 inches is overkill. I wonder why most catbacks I see online are mostly 3inches for NA. Now when you say too much then it's surely decreasing response on lower end? Now to decide on a dual cat or single cannon (I like the look of single cats but the dual looks ok too. How many miles does your ka24de have? They seem to be strong motors.

[krash]

The reason 3" piping is easy to find is because its the most common. Most people run boost and thats where bigger piping becomes more and more necessary.

However, 3" isn't "overkill" for an NA KA. If you get a 3" catback with a resonator, it would be bad at all. On my vert, I have Pacesetter headers, cat-delete (still need to put my stupid cat back in...), and then an HKS hi-power. The straight pipe (cat-delete) makes it a little louder that I'd like, but it sounded very nice with the cat in. You're not going to lose any power from going 3" over 2.5". If you do, it will be insignificant and you're not really gaining much from this, power-wise, anyway.

Also, there is no need to delete the cat. It does close to nothing on an NA KA. You should get a high flow cat, but just a regular cat will do just fine.

[Mr240dude]

Now when you say resonator its that box we have under in the middle of exhaust right? I can imagine how loud it willbe putting a catback since most of them are resonatorless. To be honest my car feels a bit more responsive mid/high range with the test pipe, it's 3 inches. I guess I will eventually get a 3inch then and see for myself. It just sucks how the header is only 2.5 there's no way I can install that then? I guess if worse case scenario I will get a high flow cat incase its too loud, im usre the silencer isn't going to aid much huh?

[krash]

No, it should work. The flanges should be the same size. My pacesetter header is also 2.5", but its bolted to a 3"test pipe which is bolted to a 3" catback. Before, it was 2.5" header to factory cat to 3" catback.

[Mr240dude]

No, it should work. The flanges should be the same size. My pacesetter header is also 2.5", but its bolted to a 3"test pipe which is bolted to a 3" catback. Before, it was 2.5" header to factory cat to 3" catback.

Cool, thanks Krash, I shall go ahead and get my 3inch cat and a 2.5 header soon.

[Hooked on 240]

Bought it in 06 with 144k and had 252k on it the day i sold it. I rebuilt it once in 07 to all stock specs.. just a refresher. Never leaked/burned/etc. I still wonder why i sold it.. most reliable car i ever had.