do i need a re-map?

[verminator]

I was running my 4.2 with de-cats and standard back box. I have now taken the back box off and replaced the last section with sports pipes. The car still goes well but doesn't pick up quite as well from low revs. It is now bloody loud and pops and bangs on the overun, so i love them. Do you think i will have to have it re-mapped? Gotta say though, i cant really justify spending £700 on a re-map. What do you think?

[gruffalo]

try phoning TVR power, tell them your set up and they may well have a map that suits that they can put on a chip and post for you, I did that cost £200 I think and work great, noticable increase in drivability and power.

[spongy]

You should be ok not getting it remapped in my opinion.I put sports pipes on mine and she has been fine

[Gazzab]

What pipes are they?

[Gray_101]

Cheap sport pipes are a pet hate of mine, they may sound great but after back to back testing on a rolling road its been found that alot of them will reduce horse power compared to the standard TVR back box.

The best off the shelf ones ive come across in my years of ownership are the ACT big bore full system and Sliverstone performance full system. if youve got one of these fitted and the cars down on power then a re map may be needed, but make sure your cam timing and valve clearances are done before the re map or you will not get the full benafit

i went for a custom big bore system from RP in the end, my tunning results for my weak 4.2 were

cheap sports pipes fitted + decat + remap = 340 bhp

standard TVR back box + decat = 357 bhp

Rp custom system with custom decats = 369 bhp ( and that was at only 84 % throttle )

[verminator]

That really is quite a difference. The pipes I have were quite cheap, so it is possible that they could be lacking in power, but it is difficult to tell. Maybe i'll just stick the standard back box on. At least i know what im'e getting as its been on Austecs RR and made 345 bhp before the de-cat.

[verminator]

By the way that figure was at the fly. Also in answer to the question of what pipes are they, I bought them from someone who had them made. My TVR man had a look at them and reconed that they were of good quality and fitted well. I love the sound of them, shmbo hates them, dubious output, mmm dilemma. Out of interest what sort of bhp is gained from a 4.2 when it is de-catted?

[robsco]

Happy to be corrected on this, but I was under the impression that decatting was something to improve the noise rather than as a way of increasing power. Something small, probably 5-10bhp were my thoughts.