LS

Im aware their is a lot of posts on this but cant find answer to this specifically. I am wanting to remove my mufflers and resonator because i like the noise having heard a few videos,leaving the cat in though for emissions. I have read conflicting information about exhaust backpressure. Is it bad for the car if i remove sections of the exhaust or will the ecu compensate for the change in backpressure? Some people say it affects your low end torque but you gain top end torque? Also i have heard this difference in back pressure is somehow linked to fuel economy so by removing sections your mpg will drop? Whereas other people say the mufflers/resonator are restricting exhaust flow and by removing them you increase your mpg... Bit confused here. Any help appreciated

Also the revs etc have all settled back to how it was before i had the timing belt done..

Justt thought i would update this as problem is now resolved. It slowly improved the more i drove and now economy is back to normal...20mpg hahah. Im guessing it was maybe ecu relearning or something a few people suggested that but i have no clue. So if happens to anyone else i would suggest waiting it out a month or two and take it on few motorway runs etc

Completely agree with you however the main reason is i need new tyres and it will cost me around £200 for a semi decent pair, whereas i can get alloys and almost new tyres for the same price

Dont know if this is in right section but couldnt find anything tyre related in drop down list. Just wondering whats the maximum tyre size that can be fitted to the ls400? I currently have 245/40/18 if anyone has bigger let me know please. Someone is selling range rover alloys cheap which are 275/40/20 but i dont know if they will fit or compromise handling etc. I know 20 inches will fit, its more the width im unsure of.

Thanks for that mike i will have a look over the rules etc. Right i think theres a good chance its that steve, because my revs are sitting a lot higher than before. Before my service: Cold start : revs just below 1k rpm When warmed up: revs settled around 500rpm After the service: Cold start: revs just below 2k rpm When warmed up: revs settled around 1k rpm Would you recommend taking it back to the garage for that or is it fairly straight forward to do yourself?

Not sure if this is under correct category but im new here. Basically i used to average around 17 mpg in the city, which was slow start/stop driving. I would get 40 miles out of £10 petrol. I then got timing belt/fan belt kit replaced, new water pump, idlers etc and a full service. I now get 40 miles out of £15 and have done around 70/80 miles since having the work done. I've read a lot of conflicting information, some people saying garage may have knocked a few sensors etc out of alignment or spark plugs may be loose. However also heard that apparently as battery would have been disconnected this resets the ECU and the car will have poor mpg until it re-learns my driving habits etc. One thing i noticed soon as i picked the car up was when i started it there was a split second clunk noise which sounded like it came from under drivers side at front of car. However only happens occasionally and as usual didn't happen when i told the mechanic. Not sure if related in any way. I doubt it is the o2 sensors etc as some people have said on other forums because it was immediately after i picked the car up. Also i always fuel up as soon as the petrol light comes on however when i picked the car up and put petrol in it barely budget above the limit when the light comes on. Therefore im guessing the garage must have really drained the fuel tank so i dont know if this maybe affects the ecu in any way because i know that is bad for the fuel pump. Dont know why they would have done that as i left plenty of fuel in the car for them. Any advice is appreciated because i dont really know what to do