JoeK Posted May 22, 2017 Share Posted May 22, 2017 Hi guys, still new to this sort of thing but starting to get some parts in for the 350 (only owned for 2 months) going to start with the exhaust because its 2004 and still running the stock exhaust and its pretty badly rotted, leaking exhaust gasses so wont make the MOT in November. Its feeling abit flat in places as well, not down to the exhaust but i am going to get a remap to try and gain some horses back and i imagine its best to that after the exhaust has been done. Anyway, rambling. First question: Whats everyones thoughts on Japspeed K4 cat back system? its cheap and boasts good figures (unlikely figures i imagine, but still)? And what are the likely figures to get from a remap, most places average a gain of 20 bhp and 20nm but i have found a place in leicester that advertises double that? Again, thoughts please? Quote Link to comment Share on other sites More sharing options...
Jetpilot Posted May 22, 2017 Share Posted May 22, 2017 (edited) Bet they dont guarantee that ; ) an exhaust on its own will make little to no difference figures wise, you will need a plenum spacer and hfc's or decats to get 20bhp ish. Edited May 22, 2017 by Jetpilot Quote Link to comment Share on other sites More sharing options...
JoeK Posted May 22, 2017 Author Share Posted May 22, 2017 Yh i thought as much, is the K4 Jap Speed worth the £500.00 price tag? Quote Link to comment Share on other sites More sharing options...
Jetpilot Posted May 23, 2017 Share Posted May 23, 2017 They are pretty much the cheapest out there and a lot of people suffer with poor fitment and quality, the choice is really dependent on the sound you want, none will make any real difference to hp. Quote Link to comment Share on other sites More sharing options...
TheSedge Posted May 23, 2017 Share Posted May 23, 2017 I'm doing same, I bought a cobra sport full catback system after looking at a few others not sure of any gains but the sound is amazing. Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
coldel Posted May 23, 2017 Share Posted May 23, 2017 Japspeed are known for poor fitment on 350z's - you are better off going for Cobra as above. Forget about gains, seriously, unless you got deep pockets. I got a milltek exhaust, motordyne plenum spacer, berks sports cats, encolsed stillen CAI and a remap and made barely 20bhp after the remap. Thats not the point though (peak gains is a pointless figure and generally means nothing in terms of actually driving the car) you need to look at area under the graph across the full rev range. The 350z is not a numbers chasing car in terms of BHP, unless you go forced induction. I got more peak gain on my R33 Skyline by replacing the turbo actuator with a £120 HKS replacement than I did spending nigh on £1500-£2000 on parts for the Zed. 2 Quote Link to comment Share on other sites More sharing options...
JoeK Posted May 23, 2017 Author Share Posted May 23, 2017 Thanks guys! My uncle went to a place in birmingham in got a custom exhaust fitted, makes a good noise and fitment is very good. He paid £500.00, same as a jap speed, i was leaning towards the advertised "performance" exhaust as i thought it might make a difference. Like i said, new to this! All my cars have been diesel and only recently started in the car scene and interested in modifying. I was focussing on the power because like i said, it felt a bit flat. The cars awesome fun, very rear happy with the ESP off so its a great toy! Suppose im thinking too much into the bhp figures. Thanks for the help though Quote Link to comment Share on other sites More sharing options...
coldel Posted May 23, 2017 Share Posted May 23, 2017 First thing you should do is stick it on the dyno for a power run (thirty or forty quid) and see what the power output looks like, should be nice and linear. If you can see any flat spots then an uprev (the Nissan version of a personalised remap) will create a better drive for you. Breathing mods will always help in that respect - but I would advise you aim for a better drive as your motivation over bhp increases as you will be slightly disappointed with the latter. Quote Link to comment Share on other sites More sharing options...
Jay84 Posted May 23, 2017 Share Posted May 23, 2017 I fitted HFC's , and although I don't know what the power difference is yet as I'm still saving for a remap, It made the whole rev range feel smoother and more responsive. I've combined mine with a plenum spacer and replacement panel filter. The rest of my exhaust is standard as my SO wont get in if its too loud as she's very prim and proper lol. Also its not corroded yet so I haven't got a good excuse. 1 Quote Link to comment Share on other sites More sharing options...
Olly350z Posted May 24, 2017 Share Posted May 24, 2017 Can confirm fitment issues regarding japspeed products, ive owned two of there exhausts and both suffered issues. The key issues are tips not being symmetrical, and resting on the W brace Recently fitted there K1 system and absolutely love the tone and pitch, but its just too bloody loud. Either or im getting old! Wìll have an extra silencer added to it snd it'll be perfect then 1 Quote Link to comment Share on other sites More sharing options...
davey_83 Posted May 24, 2017 Share Posted May 24, 2017 Any pictures of the custom system and which outfit in Brum did the work? Quote Link to comment Share on other sites More sharing options...
JoeK Posted May 24, 2017 Author Share Posted May 24, 2017 Davey_83, it was tip top exhausts. If you go on youtube and look at their page, there is a silver 04 plate, i think its the only 350 on there. The video doesnt do it justice though, sounds better when your stood behind it. Quote Link to comment Share on other sites More sharing options...
coldel Posted May 24, 2017 Share Posted May 24, 2017 I think most Youtube vids never really give you a proper feel for exhaust sounds. As for HFCs, on most cars I have owned the general consensus is that the cats are big restrictors on power increases. HFCs offer a nice midway point between cats and decats where you can put it through an MoT but see gains over a cat. 1 Quote Link to comment Share on other sites More sharing options...
Zeezeebaba Posted May 27, 2017 Share Posted May 27, 2017 A decent map should make the throttle more responsive and optimise air fuel mix ratios. You may find the car is running quite lean before a map. Berk HFCs are a popular mod but others are available. Can't comment on the exhaust your thinking of as I went for a Miltek system. A decent full service including new plugs before a map will maximise gains. Results on 350s vary widely and this in part is down to the condition of the engine and whether previous owners looked after it etc. I can only quote my car as an example and as stated condition pays a part here. I have a lowly DE and I've been lucky the cars engine was strong to start with. Obviously the dyno figures I'm going to quote are not an exact science and vary widely between garages. The results I only only use as an indication of gains rather than a true result. My car is a 2004 and was modded at approx 89k miles.All done at the same dyno at HDEV 1) Pre mods stock dyno was 281bhp 2) Miltek + Berk HFCs + Uprev was 295bhp 3) Plenum spacer + plug change+ 06 airbox 306bhp. As a point of note the car wasn't re mapped at point 3 just dynoed. It may produce another few bhp if redone but I'm happy with it. The main benefit for me was the improved drivability esp on the throttle. It was a bit lacklustre before but it feels more linear now. Quote Link to comment Share on other sites More sharing options...
chefey Posted May 31, 2017 Share Posted May 31, 2017 Hi.... When you say the car seems flat a bit, has the engine been serviced lately? Plugs filters etc, first place to start before any mods. Quote Link to comment Share on other sites More sharing options...
JoeK Posted May 31, 2017 Author Share Posted May 31, 2017 Hi.... When you say the car seems flat a bit, has the engine been serviced lately? Plugs filters etc, first place to start before any mods. Hi, when i got the car i did an oil and filter change and air filter but not the spark plugs. I am going to service it again when i come back from holiday an change the plugs then. It says in the manual platinum tipped which are £12.00 a plug. Is platinum definitely required? Quote Link to comment Share on other sites More sharing options...
coldel Posted May 31, 2017 Share Posted May 31, 2017 No its not. Platinum will last longer, but standard copper are fine and perform to the same level, you simply need to change them sooner. If you are using it as a daily go platinum, if its your weekend car copper are fine. Quote Link to comment Share on other sites More sharing options...
Ricksta1980 Posted June 2, 2017 Share Posted June 2, 2017 I fired a plenum spacer, pop charge intake, lightened fly wheel, racing clutch, de-cats and scorpion system-sounds amazing and very loud when on the throttle, quiet on tick over Quote Link to comment Share on other sites More sharing options...
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