Answers to your Questions:
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1. How much is servicing?
Very subjective. If you use Motul, the overall bill will tip RM400-500 (just oil and oil filter + labour). If u use shell semi synthetic and play it safe (without revvving and all, like having a 14 inch dick but use a 4 inch condom), it'll be 200+.
Like i said, it's quite subjective, sometimes u just change engine oil but when u do change gear oils, it'll be costlier, especially if u r using the 6 speed getrag gearbox. Be prepared to burn holes in yr pocket.
Differential Oil, well, u can either use the cheap Penzoil or watever LSD lube. If u're running full lock or 1.5 Way LSD and running 500bhp and above... different story.
Radiator coolant = quite standard.
Brakes = aaahhhhh... front discs RM1.8k, rear discs RM 1.8 per set... endless 2 pcs. Stock monoblock discs are RM1k per set.
Other than that... err... i think dat's just about what i can think of right now..
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2. If i overhaul the engine how much?
Contrary to what people believe, the 2JZGTE is not as bullet proof as it will be if it's been an abused motor from the start. I played it safe and re-built a spare engine. A set of clevite race bearings, lightening and full balancing of the engine will set u back at about RM 3-4k or so. That is, provided your engine is in a good condition. I was lucky that the spare engine came in pristine condition and the piston rings were untouched...
Metal gasket pricing again, is quite subjective. I've used HKS, (RM 1.8k), GReddy (RM 1.4k) and the best bang for buck, Cometic head gaskets = slightly over grand.
Cams = RM 5k, if you're going for 272' high lift HKS cams.
Cam Gears = RM 1 to 2k or so. but dont ever get HKS cam gears, it'll eat into yr fuckin timing belt.
Power Belt timing belt = 800 or so
Aluminium Radiators = FRC: RM 4k and Fluidyne will cost u about 3.8k
Aircond compressor about rm 900 (even if it's refurbished)
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3. If i change from auto to manual how much?
Dont fuckin bother. Dont take short cuts i.e buy auto then convert manual. The price and time consumption is just not worth it. Gearbox alone will cost u RM 8k. Clutch set, if u take HKS or Ogura It'll be RM 5k. Best bang for buck i'd say is the ACT clutch. Putting that aside, u need the pedals, the clutch pumps, flywheel and etc. shit loads of parts to source hence shit loads of headache.
Long shaft, rear diff, etc. all gotta change. EVEN THE REAR DRIVE SHAFT too!
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4. Reliability?
If you do it right, mechanically, electronics and tuning. U can rape her continously without blowing it. Infact, it'll enjoy being raped endlessly and u'll enjoy it to.
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and anything else that you think i should know...
5. Road tax's a bitch.
6. It's getting old
7. U need to spend a fair bit fixing here and there to get it in pristine condition esp. if u buy it from dodgy 2nd hand shops.
8. Did i tell u road tax's a bitch? oh yeah.. i did..
9. Alot of people claim they can do 2JZGTE JZA80 but they are just bull and craps. I only go 1 place for MAJOR WORKS, that is: GT AUTO SUNWAY. The rest are just for part sourcing and price comparison.
10. Some people claim petrol consumption's a bitch. Well i tell them that's because some of them "did not do it right".. I'm running more than 600ps and i'm getting 400km for full tank on city driving and 470km for outstation drives.
12. Did i tell u 2jZGTE loves nitrous? oo.. they love it..
13. Not many shops carry JZA80 or 2JZGTE parts. Infact, u can count it with 1 hand if u go sunway.
14. Don't worry. I know where to source it.. bwahahahaha
:)